I usually freestyle, typically meaning a frenzied session of anywhere from 4 to 16 hours (obviously with breaks). I enjoy the feeling of timelessness when I write. Helps me stay in the moment and focus solely on the work.
Aiming for a word count never worked for me. I find it super distracting, and it messes with my flow. I've caught myself using long phrases where a succinct word or two would be better, solely to reach my quota faster. Guess it's because I'm a lifelong gamer and therefore wired to want to fill up bars of things and fabricate higher numbers. That's just no good.
I've found some success with timers, though. I've tried now and again to create a kinda-sorta normal workday for myself, to get away from my normal frenzy -> burnout -> inactivity cycle. It sort of works, but I'm not a creature of routine (okay, so I'm undisciplined) and I haven't yet managed to stick to it for very long. Just knowing there's a timer lurking in the background stresses me, if only ever so slightly, and often makes me try to churn out words faster at the cost of quality. Haven't given up on it, it's something I could probably get used to.
So yeah, the best thing for me is a freestyle frenzy for new drafts, and mellow tinkering for revisions.