The sliding window technique - when to use it and common patterns

I struggled with sliding window for the longest time until I realized there are basically 3 patterns:

Fixed size window: Easy. Just maintain window of size k.

• Max sum subarray of size k
• First negative in every window

Variable size (find maximum):

• Longest substring without repeating characters
• Longest substring with at most k distinct characters
• Max consecutive ones with at most k flips

Variable size (find minimum):

• Minimum window substring
• Smallest subarray with sum >= target

Once you categorize, the approach becomes mechanical. Anyone have additions to this?