I ALWAYS tune before playing and check periodically during a session just in case.
Phone app tuners are great in a quiet environment, like home practice, but at a jam session, with all the ambient noise, I found them useless most of the time, unless, you can plug them directly into your phone via an interface.
I always wanted a Peterson strobe tuner but the price was just too high.
I then discovered the Istrobosoft phone app strobe tuner by Peterson. It works great and I use it all the time rather than a Bass headstock tuner. It is cheap and works fantastic. Here is a link to a topic that has all the details regarding it.
Bass tuner
When I started into Bass at the beginning of 2021 tuners were one of the surprises that I got.
I have a few acoustic and electric guitars and my headstock tuners that work great on them were either too erratic or plain just did not work on my Bass. Another big surprise is I was having to buy a Bass specific amp. Because I jam a lot I will not buy amps with less than 100W. Enter the Rumble 100. 