I'm with four bands right now. Seems each band has one place they book regularly... and not much else. Is that how it is now?
I'd much rather have one band that books several places. Four bands' worth of songs to learn is a bit much! I don't have enough study time for that.
I don't think there is any such thing as "how it is now". From my perspective, there are as many ways to book gigs as there are venues or bands.
Personally I've seen that some bands do grace some venues regularly as in they play a gig every month or two at the same venue. But I've not seen it where the band only plays that venue - outside of a "house band" type situation anyway. I've actually experienced that the bands I've played in tend to play a lot of the same venues.
Your post seems to contain two completely separate rants though. Yes, managing music for 4 bands is a lot of work - but that's easily fixed if it is a problem. Sure we'd all like to be in the "perfect band", that plays exactly the amount that we prefer, has access to lot's of good paying venues, has a playlist that keeps us interested and has solid leadership and members that do what it takes to make it work. Few of us ever get this so we do what we have to to find or happy place. I
love having multiple projects (and especially like doing sub work), but keeping track of 4 sets of playlists would be daunting. Having overlapping songs is both a blessing and a curse (it's not unusual that I have to have multiple versions of a song prepared because the different band's play it just a bit different). Even if they play it the same, for me, it's just an opportunity to get burnt out on the song that much quicker.
It sounds to me like you need to find a couple of bands that play out more so you can get the stage time in that you need but don't have to keep up on 4 play lists.