Use it in a few places

src/libraries/Common/src/System/Net/CookieComparer.cs

@@ -24,8 +24,8 @@ internal static bool Equals(Cookie left, Cookie right)
 
         internal static bool EqualDomains(ReadOnlySpan<char> left, ReadOnlySpan<char> right)
         {
-            if (left.Length != 0 && left[0] == '.') left = left.Slice(1);
-            if (right.Length != 0 && right[0] == '.') right = right.Slice(1);
+            if (left.StartsWith('.')) left = left.Slice(1);
+            if (right.StartsWith('.')) right = right.Slice(1);
 
             return left.Equals(right, StringComparison.OrdinalIgnoreCase);
         }

src/libraries/System.Diagnostics.Process/src/System/Diagnostics/Process.Windows.cs

@@ -674,7 +674,7 @@ private static void BuildCommandLine(ProcessStartInfo startInfo, ref ValueString
             // problems (it specifies exactly which part of the string
             // is the file to execute).
             ReadOnlySpan<char> fileName = startInfo.FileName.AsSpan().Trim();
-            bool fileNameIsQuoted = fileName.Length > 0 && fileName[0] == '\"' && fileName[fileName.Length - 1] == '\"';
+            bool fileNameIsQuoted = fileName.StartsWith('"') && fileName.EndsWith('"');
             if (!fileNameIsQuoted)
             {
                 commandLine.Append('"');

src/libraries/System.Memory/src/System/Buffers/SequenceReader.Search.cs

@@ -142,7 +142,7 @@ private bool TryReadToSlow(out ReadOnlySequence<T> sequence, T delimiter, T deli
                 else
                 {
                     // No delimiter, need to check the end of the span for odd number of escapes then advance
-                    if (remaining.Length > 0 && remaining[remaining.Length - 1].Equals(delimiterEscape))
+                    if (remaining.EndsWith(delimiterEscape))
                     {
                         int escapeCount = 1;
                         int i = remaining.Length - 2;

src/libraries/System.Private.CoreLib/src/System/IO/FileStatus.Unix.cs

@@ -168,7 +168,7 @@ internal bool IsFileSystemEntryHidden(ReadOnlySpan<char> path, ReadOnlySpan<char
             return HasHiddenFlag;
         }
 
-        internal static bool IsNameHidden(ReadOnlySpan<char> fileName) => fileName.Length > 0 && fileName[0] == '.';
+        internal static bool IsNameHidden(ReadOnlySpan<char> fileName) => fileName.StartsWith('.');
 
         // Returns true if the path points to a directory, or if the path is a symbolic link
         // that points to a directory

src/libraries/System.Private.CoreLib/src/System/IO/Path.Unix.cs

@@ -137,7 +137,7 @@ public static bool IsPathRooted([NotNullWhen(true)] string? path)
 
         public static bool IsPathRooted(ReadOnlySpan<char> path)
         {
-            return path.Length > 0 && path[0] == PathInternal.DirectorySeparatorChar;
+            return path.StartsWith(PathInternal.DirectorySeparatorChar);
         }
 
         /// <summary>

src/libraries/System.Private.CoreLib/src/System/Type.Helpers.cs

@@ -508,7 +508,7 @@ private static bool FilterNameImpl(MemberInfo m, object filterCriteria, StringCo
             }
 
             // Check to see if this is a prefix or exact match requirement
-            if (str.Length > 0 && str[str.Length - 1] == '*')
+            if (str.EndsWith('*'))
             {
                 str = str.Slice(0, str.Length - 1);
                 return name.StartsWith(str, comparison);

src/libraries/System.Security.Cryptography/src/System/Security/Cryptography/Helpers.cs

@@ -84,7 +84,7 @@ internal static byte[] LaxDecodeHexString(this string hexString)
 
             ReadOnlySpan<char> s = hexString;
 
-            if (s.Length != 0 && s[0] == '\u200E')
+            if (s.StartsWith('\u200E'))
             {
                 s = s.Slice(1);
             }