An afternoon. Probably started on the next one that same evening.
I've always hated poring over tracks with a fine comb and going back on ideas. I've never made anything better that way..
Before I got started with electronic I was playing funk and punk so rawness and spontaneity has always been always a huge factor with all my music.
Even if I go back to a track a few days later, the vibe is different, I'm different... and I usually end up killing what made me dig the original version.
This does totally mean that my mixes sounded like utter shit for many years, though. I'm not saying this is the best approach, but iteration isn't everything either.
It did teach me to get A LOT of ideas down quickly and has given me giant catalogue of stuff (tracks, loops, samples, crap) to go back to... and I never have the sense that
'I can't do this now because I already did it in track so and so'
My process has gotten a bit more involved, so it takes longer now.. but the basic idea is still the same: Put something down one day, DON'T overwork it.
Rinse the crap out of it at night, take it out for a ride and then finish the next day... and then on the next (even better) one.