Here's my two cents on timekeeping.
I've been working on playing with the click at very slow speeds, 10 bpm right now but in reality, I'm playing at 40 bpm with the click on the first beat only. I do that for long periods of time and I noticed it helped my timekeeping a lot. The thing I notice the most now is that I'm much more aware of when I speed up or when I slow down. By practicing very slow, you start hearing those things a lot better. Apparently that Jeff Porcaro, Steve Gadd and Matt Chamberlain practiced these kind of things back in the day.
I've also practiced an exercise that Gavin Harrison shared somwhere, maybe on this very forum. You start by listening closely and memorizing the click at 60 or 70 bpm (sing it to yourself) and then, stop the click, start the recording machine and count yourself in by clicking the stick four beats and play a bunch of bars. Then listen to yourself back and play the click over your recorded performance. You obviously want the click to sync with your recorded performance. This is very hard but really worth working on. When you get more confortable with this, start changing the subdvisions while you play. It's definitely hard.
You can also practice your usual exercises (rudiments, coordination, new breed, whatever) with the click on odd places in the bar. On all eight notes upbeats, on the and of 1, on all upbeat 16ths, etc. This will also be hard but again, worth it.
All these suggestions are technique based things. You should get yourself in playing situations where your time will be challenged too but now with real human beings, not a metronome. Try to always record yourself, whether it's rehearsals or shows, that's what I do. This way, I become aware of all tendencies I might have when playing with people.
Hope this all helps and best of luck in all your time endeavors.
Daniel
www.danielbedarddrums.com/en/