Good timing reduces risk and gets you in to fast part of a trend or a swing move.
While there are others things like equity selection and risk or leverage that determine your returns , crux of active trading still boils down to timing.
Momentum burst kind of swing trading methods try to time entry as soon as momentum is established. And the expectation is the momentum will continue immediately and accelerate. Or they buy just before the momentum burst anticipating start of a move.
If you time your entry after a move has started chances of trade failure is high. Especially for momentum burst kind of impulse short term moves of 3 to 5 days there is an edge in timing of entry and exit. If you enter a swing trade say on third day instead of first day of breakout, sometime it might work but then you do not have much edge.
Different setups and different kind of instruments require different kind of timing edges. The Lemonade Strategy for 401K I trade is at the heart a timing strategy. It times entry near extreme weakness in breadth. That ensures you are getting in at end of established bearish trend and entering at beginning of a new bull trend. Same way it exits near the end of established bull trend and avoids the down move. That is the only reason the strategy has avoided losses in all 14 years of use.
Timing entry and exit creates edge for traders, if you want to make money trading find right time to enter and exit.