I practice pretty strictly but I have a problem missing time, usually because I'm travelling or something, you know... stuff comes up right? Like recently I broke strings on my Ibanez and had difficulty with the lo-trs system. It took me almost a week to get it back into it's original shape! And yes, my speed declined noticeably, but it took maybe 6 hours or so (spread out over a couple days) to get my speed back to where it was. So missing time isn't the end of the world, you can always get it back.

The amount of solid, good technique you have will judge how long it takes to get it back after you go on haitus for a while. And sometimes breaks can be good (I'm actually faster now, after that break).

But missing a day? That's nothing, I wouldn't worry about it.