That is how trading works, different time of deposits and withdraws gives different results. and we can see it specially in cryptocurrency exchange because of the volatility in the market.
I agree, it is important that we know when to sell and when to buy if we really want to gain a good profit out of our investment. Also, it is best that we have enough wisdom about what we are doing. As for me, It is not just the right time of buying that matters, it is also our patience and ability to wait and sell at the perfect timing.
You also need experience and good analysis to learn when is the perfect timing. It requires a lot of practice that sometimes will cost you so much.