As others have noted, it really depends on whether you can trust the promise of "one more week" and "bare bones." If I had reason to believe that a former employer would stick to that, and if I got it in writing ("schedules and index ONLY"), then I'd do it; but then I need the money more than you do at the moment.

In any event, I'd also be prepared, if approached for "one more week, round two," to say "absolutely not" in a really unambiguous way. One extra week I can see -- your manager's in a pinch -- but any more than that and somebody's trying to take advantage of your guilt and/or your erstwhile goodwill.

You've been looking forward to ditching this job for so long -- I don't want it poisoning your time off.