What a good GPC script actually looks like

Most GPC scripts in circulation share a family resemblance: a wall of if statements, timing values hardcoded inline in six different places and no indication anywhere of what a given number represents or when it was last correct.

They work until they stop working, at which point they become unfixable, because nobody including the author can tell which of the six 612s is the one that needs to move.

Three things that separate maintainable GPC from the rest

Name your constants. Put a define at the top with a comment explaining what the value represents and when it was last validated. If the same number appears twice in the body of the script, it should have appeared zero times.

Separate policy from mechanism. The logic deciding when to release should stay clear of the code performing the release, so that when a patch moves the window you are changing one value rather than auditing control flow to work out where the decision actually happens.

Make state explicit. GPC hands you globals and very little else, so the discipline has to come from you: track what is armed, track what is running and reset all of it in one place. Most of what looks like random script misbehaviour turns out to be stale state left over from a previous input that nobody cleared.

The unglamorous stuff is the product

The interesting part of a timing script runs to about thirty lines. The rest of it, meaning menu persistence, profile storage, recovery from a dropped session and not throwing away your values on reboot, is what decides whether you are still using the thing in March.

That is the half most scripts skip, and it is where we spend most of the time.