There still seems to be questions about the portal that come up in posts on this site.
Some news about WVU's latest portal signee may illustrate some of the possibilities, but maybe not fully answer some portal questions. EERS got their 5th transfer for next season, a guard from Montana State who was first team all Big Sky Con., averaged 17 ppg., and had 27 pts. against Kansas State in the NCAA tourney. He played TWO years at Washington, TWO years at Montana State, and will play his last year at WVU. WVU also signed a guard named Silverio who played one year at Rhode Island, 3 years at Hofstra, and was at Manhattan last year when the Coach departed right before the season started. So Silverio entered the portal, along with another Manhattan player, Jose Perez, who also is now at WVU. Perez didn't get clearance from the NCAA to play in 2022-23. Both expected to play this coming season. So in Silverio's case, WVU will be his FOURTH school, and the THIRD school at which he will play basketball!
So it seems that there are a lot of variables, and that individual circumstances often come into play when determining just how many "portal transfers" can be made.