Thanks to what is an astonishingly (to me) large cache of crochet rectangles, I was able to make substantive progress toward two goals.
First, I repurposed thirty-six crochet rectangles. Here are the former crochet rectangles in all of their nearly completed crochet square rehabbed glory, needing nothing more than for their ends woven in and trimmed:

Here are the same squares several hours later with the ends woven in, trimmed, and — as the result of an impulsive decision to block them — slightly damp, but otherwise ready for adventure:

So, I not only reduced my formidable collection of crochet remnants by 36 pieces, I moved twelve crochet squares closer to my goal of one thousand squares with a total of 486 crochet squares completed, leaving me just 514 crochet squares shy of my goal.
So what is a crocheter to do?
This crocheter headed back to the same black bag with the cache of crochet rectangles for an even deeper dive for crochet remnants.
In no time I had all of the crochet rectangle remnants a crochet rehabber could want.
The only problem I had was the way the very (very) long tails tangled. After trying several things that didn’t work, I finally found that by sorting them into groups of three and gathering the exceedingly long ends into one strand and crocheting them into a chain, I was able to keep the rectangles destined for a particular square together and cut down on the incessant tangling:

With sixteen rehabbed squares to be now identified, I am nearing the halfway point of just over 500 rehabbed crochet squares, and I will spend the next couple of days working to reach that goal, one stitch at a time.
What a great tip! Crocheting three long tails into one chain to keep them from tangling! Thanks!
i have decided to join you in your quest to do a thousand squares but probably not that many I have started while my mother was in the hospital and now to do it in her name. I have ten six inch squares without tails worked in finished and more to come .