Museum pass

I'm afraid it's a matter of doing fhe math. How many of the Museums on the pass can you reasonably be expected to see during the validity period ov the pass you buy. Vs the individual single admission price of each of those museums. The more museums you cram in, the better the total cost on the pass. Assuming you only want a brief stay in each place. But if you want several hours at the Louvre and/or Orsay, for example, then the pass may provide less value. Note that you still need to make a reserved entry time, even with the pass, for those museums requiring it.

Exactly - it's not just a question of the monetary cost of the pass vs the individual tickets. It's also that you now have to reserve in advance the times to visit some of the most popular museums, thereby eliminating another past advantage of the past - flexibility.