My thought is that each time a chain is disassembled, and reassembled, one looses a few percent of the original strength for that one link. 10%? And this creates a potential failure point.
As others have mentioned, it probably isn't bad to do it a few times as long as one is using different links.
100 times per chain?
I usually do a one-shot thing. Once the chain goes on a bike, it stays on the bike until it is ready to be removed and replaced.
I've been using the HG73 9S chains. I bought a few of those replaceable pins, but seem to have misplaced them. So, on 2 chains so far, I've just pushed the pins out and back in. So far, they're at about 90% worn out without failure. I marked the link on the second chain... just so I'll know in case of failure. I ended up with a kink on the other side of the chain that had to be worked out. And, I've started carrying a chain tool... just in case.