There shouldn’t be a need for pro forma sessions in this era. The rule regarding no more than 3 days of adjournment is because back then, congress was considered a part time job, while the president was a full time job. So the president need to be able to make recess appointments because the government need to function even if congress is on vacation. In the modern world, with near instantaneous communications, this rule is unnecessary. Congress can take a 4 day break or even a week break, and vote to confirm appointments via virtual meet if they wanted to.

I mean the electoral college thatvote in December is in a way already kinda a pro forma session when you think about it. The electors used to actually vote, now they just rubber stamp what the people in their state actually voted for, and if the popular vote inter state compact passes, its even more of a pro forma session. Like the president would technically be elected by the electoral college, while actually its de facto a popular vote. The electoral college would never really go away since 37 states agreeing is almost impossible. Just like this congressional pro forma sessions, since changing the text of the constitution is too much of a hassle.