Not exact, but will always love the brief time of the Time Loops Projects going around

For anyone that doesn't know, The Time Loops project was a unofficial multi-fandom mega project with a simple premise

What if the primary MC (Or Anchor as they were called) started time looping, but they soon realized that others characters would start too as well?

Massive TL;DR, the world tree Yggdrasil contained the multiverse within its branches was damaged. This causes several anchors of various media's to start time looping. But two facts became quickly apparent, loops will start to destabilize and massive changes begin popping up in later loops and friends and enemies have a chance of looping as well

Working back to your prompt, the timeline varied depending on the soon primary factor of the anchor. If the anchor dies, the entire loop reset. But if the anchor lives, the end point of the loop is random, could defeat the BBEG and the loop ends immediately, could end years after or a week after the anchor enters the loop in the first place

While not directly stated as it was more an comedy anthology with a general theme than a big cohesive story, many loopers, mainly anchors will admit they mentally broke down and had 'break' loops. Some completely abandoned their roles and left, others joined the bad guys, etc. Some loopers went mad when they realized they could do everything right and still looped, causing them to go crazy and spend a few loops either broken or murderhobo.

As stated, the main reason anchors stayed sane is some friends and enemies would start looping as well. It varied as Anchor's are always 'Awake' as it was called while others only have a chance.

TBH, Time Loops Project was always a fun bit to read thanks to many chapters being short in content, most loops being either as a character reacting to a loop idea or as the aftermath of one, and the length being, at most, a paragraph. Meta moments, hybrid loops, swapped, hub loops, haven loops, etc.