Playing in time is important. We know that as bass players, right?! I’ve been discussing this with a group of students recently at a college that I lecture at. Frequently, especially with new and challenging tunes, a lot of players have a habit of cranking up the metronome to full speed (or even beyond!) before beavering away. This is inefficient, don’t do this!
If you are working on new material it’s important that you understand what you’re playing before you get it in time. Don’t run before you can walk. I appreciate how there is potential to measure success by targeting a certain BPM (more about SMART targets another time!), but what you end up with is a raft of material you can play quickly without actually knowing what it is you’re playing.
Speed will come. It happens naturally when we understand what we’re playing, we’re fluid with our technique and are well practiced; that’s the point at which you should be working to a click. When you are at the stage where you want to work with a metronome, check out my YouTube review (above) of one I highly recommend.