It could mean losing on time.

I think I recently lost a game on time because I forgot that our clocks went back by an hour, a couple of weeks ago.

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How is it offensive at all? People premove all the time, particularly in the opening and trading sequences. Conditional moves are just CC's premoves. Anyone offended by conditional moves have to have the most fragile personalities ever seen.

in speed chess, I often use premoves, in the few daily games I have played, I use conditional moves if and only if all the moves force a move and I know what that move is

I do not think that it is offensive

Nope, they are ok. They are VERY different from premoves. A premove could be somehow disrespectful in correspondence (also in any time format but assuming they will recapture a queen in blitz is not that much, they always do). Maybe a recapture premove (which only triggers if they capture your piece first) would be ok in CC. It ends up being some kind of conditional move (there might be multiple captures though). But a conditional gives an answer to some SPECIFIC move, it's what you would play if they play that move and not other. It's totally ok.