Wow! Yeah, that really sounds right, though I'll have to re-read the story to see if it fits. The Wikipedia article summary definitely seems right. I forgot about the town's explosion and the perpetrator of the 'experiment', though that seems very familiar! Seems my memory may be fading a bit. Awesome, thanks!

Yeah, I may have conflated two stories, I did read quite a lot of Pohl's works back then - though I have strong memories of the boat hull blocking the 'reset' signal (for lack of a better term) thus allowing the subject to escape the endless cycle... and another strong recollection of a day of the week in the title, though again, that may be due to my failing memory. I'll go read the referenced stories and see if anything jogs my memory. Thanks, all!