diff --git a/src/aces/__main__.py b/src/aces/__main__.py
index 15c6012..e28747b 100644
--- a/src/aces/__main__.py
+++ b/src/aces/__main__.py
@@ -21,7 +21,6 @@
 
 MEDS_LABEL_MANDATORY_TYPES = {
     "patient_id": pl.Int64,
-    "prediction_time": pl.Datetime("us"),
 }
 
 MEDS_LABEL_OPTIONAL_TYPES = {
@@ -29,10 +28,11 @@
     "integer_value": pl.Int64,
     "float_value": pl.Float64,
     "categorical_value": pl.String,
+    "prediction_time": pl.Datetime("us"),
 }
 
 
-def get_and_validate_label_schema(df: pl.LazyFrame) -> pa.Table:
+def get_and_validate_label_schema(df: pl.DataFrame) -> pa.Table:
     """Validates the schema of a MEDS data DataFrame.
 
     This function validates the schema of a MEDS label DataFrame, ensuring that it has the correct columns
@@ -53,7 +53,7 @@ def get_and_validate_label_schema(df: pl.LazyFrame) -> pa.Table:
 
     Examples:
         >>> df = pl.DataFrame({})
-        >>> get_and_validate_label_schema(df.lazy()) # doctest: +NORMALIZE_WHITESPACE
+        >>> get_and_validate_label_schema(df) # doctest: +NORMALIZE_WHITESPACE
         Traceback (most recent call last):
             ...
         ValueError: MEDS Data DataFrame must have a 'patient_id' column of type Int64.
@@ -65,7 +65,7 @@ def get_and_validate_label_schema(df: pl.LazyFrame) -> pa.Table:
         ...     "time": [datetime(2021, 1, 1), datetime(2021, 1, 2), datetime(2021, 1, 3)],
         ...     "boolean_value": [1, 0, 100],
         ... })
-        >>> get_and_validate_label_schema(df.lazy())
+        >>> get_and_validate_label_schema(df)
         pyarrow.Table
         patient_id: int64
         time: timestamp[us]
@@ -82,7 +82,14 @@ def get_and_validate_label_schema(df: pl.LazyFrame) -> pa.Table:
         categorical_value: [[null,null,null]]
     """
 
-    schema = df.collect_schema()
+    schema = df.schema
+    if "prediction_time" not in schema:
+        logger.warning(
+            "Output DataFrame is missing a 'prediction_time' column. If this not intentional, add a "
+            "'index_timestamp' (yes, it should be different) key to the task configuration identifying "
+            "which window's start or end time to use as the prediction time."
+        )
+
     errors = []
     for col, dtype in MEDS_LABEL_MANDATORY_TYPES.items():
         if col in schema and schema[col] != dtype:
@@ -99,7 +106,23 @@ def get_and_validate_label_schema(df: pl.LazyFrame) -> pa.Table:
         elif col not in schema:
             df = df.with_columns(pl.lit(None, dtype=dtype).alias(col))
 
-    return df.collect().to_arrow().cast(label_schema)
+    extra_cols = [
+        c for c in schema if c not in MEDS_LABEL_MANDATORY_TYPES and c not in MEDS_LABEL_OPTIONAL_TYPES
+    ]
+    if extra_cols:
+        err_cols_str = "\n".join(f"  - {c}" for c in extra_cols)
+        logger.warning(
+            "Output contains columns that are not valid MEDS label columns. For now, we are dropping them.\n"
+            "If you need these columns, please comment on https://github.com/justin13601/ACES/issues/97\n"
+            f"Columns:\n{err_cols_str}"
+        )
+        df = df.drop(extra_cols)
+
+    df = df.select(
+        "patient_id", "prediction_time", "boolean_value", "integer_value", "float_value", "categorical_value"
+    )
+
+    return df.to_arrow().cast(label_schema)
 
 
 @hydra.main(version_base=None, config_path=str(config_yaml.parent.resolve()), config_name=config_yaml.stem)
@@ -138,7 +161,9 @@ def main(cfg: DictConfig):
         result = result.rename({"subject_id": "patient_id"})
         if "index_timestamp" in result.columns:
             result = result.rename({"index_timestamp": "prediction_time"})
-        result = get_and_validate_label_schema(result.lazy())
+        if "label" in result.columns:
+            result = result.rename({"label": "boolean_value"})
+        result = get_and_validate_label_schema(result)
         pq.write_table(result, cfg.output_filepath)
     else:
         result.write_parquet(cfg.output_filepath, use_pyarrow=True)
diff --git a/src/aces/expand_shards.py b/src/aces/expand_shards.py
index 6ff5a1a..ca64a9a 100755
--- a/src/aces/expand_shards.py
+++ b/src/aces/expand_shards.py
@@ -31,9 +31,9 @@ def expand_shards(*shards: str) -> str:
 
         >>> parquet_data = pl.DataFrame({
         ...     "patient_id": [1, 1, 1, 2, 3],
-        ...     "timestamp": ["1/1/1989 00:00", "1/1/1989 01:00", "1/1/1989 01:00", "1/1/1989 02:00", None],
+        ...     "time": ["1/1/1989 00:00", "1/1/1989 01:00", "1/1/1989 01:00", "1/1/1989 02:00", None],
         ...     "code": ['admission', 'discharge', 'discharge', 'admission', "gender"],
-        ... }).with_columns(pl.col("timestamp").str.strptime(pl.Datetime, format="%m/%d/%Y %H:%M"))
+        ... }).with_columns(pl.col("time").str.strptime(pl.Datetime, format="%m/%d/%Y %H:%M"))
 
         >>> with tempfile.TemporaryDirectory() as tmpdirname:
         ...     for i in range(4):
@@ -43,18 +43,20 @@ def expand_shards(*shards: str) -> str:
         ...         else:
         ...             data_path = Path(tmpdirname) / f"{i}.parquet"
         ...         parquet_data.write_parquet(data_path)
-        ...     json_fp = Path(tmpdirname) / ".shards.json"
+        ...     json_fp = Path(tmpdirname) / "4.json"
         ...     _ = json_fp.write_text('["foo"]')
         ...     result = expand_shards(tmpdirname)
-        ...     sorted(str(Path(x).relative_to(Path(tmpdirname))) for x in result.split(","))
-        ['1.parquet', '3.parquet', 'evens/0/file_0.parquet', 'evens/0/file_2.parquet']
+        ...     sorted(result.split(","))
+        ['1', '3', 'evens/0/file_0', 'evens/0/file_2']
     """
 
     result = []
     for arg in shards:
         if os.path.isdir(arg):
             # If the argument is a directory, take all parquet files in any subdirs of the directory
-            result.extend(str(x.resolve()) for x in Path(arg).glob("**/*.parquet"))
+            result.extend(
+                str(x.relative_to(Path(arg)).with_suffix("")) for x in Path(arg).glob("**/*.parquet")
+            )
         else:
             # Otherwise, treat it as a shard prefix and number of shards
             match = re.match(r"(.+)([/_])(\d+)$", arg)
diff --git a/src/aces/predicates.py b/src/aces/predicates.py
index 7e26e2a..752fe6d 100644
--- a/src/aces/predicates.py
+++ b/src/aces/predicates.py
@@ -291,9 +291,9 @@ def generate_plain_predicates_from_meds(data_path: Path, predicates: dict) -> pl
         >>> from .config import PlainPredicateConfig
         >>> parquet_data = pl.DataFrame({
         ...     "patient_id": [1, 1, 1, 2, 3],
-        ...     "timestamp": ["1/1/1989 00:00", "1/1/1989 01:00", "1/1/1989 01:00", "1/1/1989 02:00", None],
+        ...     "time": ["1/1/1989 00:00", "1/1/1989 01:00", "1/1/1989 01:00", "1/1/1989 02:00", None],
         ...     "code": ['admission', 'discharge', 'discharge', 'admission', "gender//male"],
-        ... }).with_columns(pl.col("timestamp").str.strptime(pl.Datetime, format="%m/%d/%Y %H:%M"))
+        ... }).with_columns(pl.col("time").str.strptime(pl.Datetime, format="%m/%d/%Y %H:%M"))
         >>> with tempfile.NamedTemporaryFile(mode="w", suffix=".parquet") as f:
         ...     data_path = Path(f.name)
         ...     parquet_data.write_parquet(data_path)
@@ -316,7 +316,7 @@ def generate_plain_predicates_from_meds(data_path: Path, predicates: dict) -> pl
     """
 
     logger.info("Loading MEDS data...")
-    data = pl.read_parquet(data_path).rename({"patient_id": "subject_id"})
+    data = pl.read_parquet(data_path).rename({"patient_id": "subject_id", "time": "timestamp"})
 
     if data.columns == ["subject_id", "events"]:
         data = unnest_meds(data)