I have never liked or needed clip on tuners. The most basic requirement of my basses that I gig with is that they stay in tune for a minimum of 1 set. I use my tuner at most once before each set and 99% of the time, that is only to verify tuning. My pedal tuner is plenty adequate and convenient for that and it is more reliable than clip ons.
This is pure anecdote, but I'm sure there are other situations that lead to the same outcome.
Not long ago I was playing at a venue that had some kind of curtain of LEDs at the back. Very light wiring. I was stage right that time, and I turned to the drummer between songs for some reason, and my headstock got caught in the LED curtain. I shook it lightly but all I did was wrap more wire around a couple of tuners. I pulled harder... it wasn't doing anything and I feared I'd make the whole thing drop on the drummer's head, which would be hilaaaaarious, no doubt, but not what I had in mind. Fortunately somebody came to the rescue, untangling the wires from my headstock, all while I was playing (singer hadn't realised what was going on with me or heard the drummer laughing, we're a 7 piece). Eventually I was freed, but a couple of strings were slightly off. Make one note last a whole beat while I turn the clip-on tuner on, and I could 'see' as I was playing exactly just how off I was and corrected it on the fly.
My tuning is stable as is most people's, but... things happen to interfere with tuning happiness while onstage.
They're handy little things, but they're not the only way, of course. Just saying that no matter how stable your bass is, things happen, like a guy who joined us singing for a couple of songs, comes on stage from behind me and rather than announcing his presence to me somehow, he (gently, I admit) moves my bass neck aside... by holding it at the headstock and slightly detuning my D string...
I would always have some kind of tuner ready, whether clip-on or as floor tuner.