Apparently the time jumps were prompted by ~real life. Masters and Johnson had a looong period of doing research where not much interesting happened, and their first book wasn't published until after they'd been working together for like 10 years. So the show had to start moving quickly in order to get back to the interesting stuff.

Expect the time jumps to become more of a regular thing, too, since their relationship lasted into the 80s, and we're still at 1960 after 2 seasons. They're picking up the pace.