I believe if you are not using it then you do have to sign back in after a while. I think 2021 is the same as 2020 as far as this goes.

Yes, but the benefit of this 2-step was to extend the time-out to much longer period.  I found the Inuit notice: 

With current IRS security requirements your tax software login timeout occurs after 30 minutes of inactivity, however the IRS is extending this to 12 hours starting sometime in January. This change is due to the expectation that Tax Pros will have adopted two step verification to make their software login more secure. 

ProSeries will extend the login timeout in February. 

When, February 29?

It should be 0 hours and 0 minutes. What a bunch of crap. Just my opinion.

ProSeries promised 🙄 that when we abided by the two step verification mandated by the IRS beginning this January, they would update by end of February to follow the IRS-allowed 12 hour time-out.

With current IRS security requirements your tax software login timeout occurs after 30 minutes of inactivity, however the IRS is extending this to 12 hours starting sometime in January. This change is due to the expectation that Tax Pros will have adopted two step verification to make their software login more secure. 

ProSeries will extend the login timeout in February. 

My calendar says March 5.

90 minutes timeout is not 12 hours, ProSeries.

Well, it's close.  Well, at least someone at Intuit thinks it's close.  Intuit isn't very good with numbers.