Is this really what a lot of people do? Learn 4 or 5 songs, in one hour?
Very often I will just put the radio on and jam along with songs I've never heard before. I pretend I got hired for a cover-band gig at the last minute, I'm live in front of an audience, and this is my one and only opportunity to nail the songs. I need to be hyper-focused and aware to pull this off! If the chord changes don't pop out at me in the first few seconds (and they very often do), then I will sit out the first verse, listen carefully, and come in on the downbeat of the second verse.
I have a
terrible ear, I mean I am
really bad at picking out the right notes by ear, so surely I am not the only bassist with the ability to learn simple radio-friendly songs by ear, in real time, am I? Most pop/rock songs share a certain structure, so it's not like we have to reinvent the wheel each song.
Then I might go back, choose a few songs that I particularly liked (or that gave me trouble), and give them a second (or even third!) pass for further improvement. If I haven't learned it after three passes, then I will set that song aside for future practice. I can't imagine repeating the same song four or more times
in one sitting; that sounds to me like a frustrating use of practice time!
The exception of course is if I have a paying gig. Then I will do whatever needs to be done to get things right for the gig. But sometimes we do not have a chance to prepare the songs in advance of the gig (pickup jazz, open mic, blues jam, subbing, etc.) so a versatile bassist should have the ability to "fake it" through a song on the first try.