does it vary for different coins? I'm asking because if I want to day trade I want to make sure its doable. Someone told me it takes a long time to have a buy go through and a sell.
In trading, there is usually no prediction as to when there will be an increase. It all depends on the market and the coin involved.
The length of time to hold depends on when you see the desired % of profit. It could be in weeks or days or can take longer.