Take advantage of museum free times, or too crowded?
I'm visiting Madrid for the first time in mid-June for a few days. I love museums and I'm really excited that Madrid has so many. I will be there during the free days/times for some museums (like Prado museum, 6-8 PM or Sunday 5-7 PM, and Thyssen-Bornemisza on Mondays). But I'm wondering what the crowds are like and if it's better to just pay and go at a different time. There is also the pass that includes 3 museums and it's about 33 EUR which is not so, so much for 3 museums. But there is a lot of stuff I want to do and see in a short time... I'm just not sure as I have never been... I did see some older posts about this but things have changed a lot in the last few years regarding travel and crowds.
I appreciate any advice!!
EDIT: thanks so much, everyone! I've gotten even more advice than what I asked about and I'm so appreciative!