Yes; it is very important to do the fuel tank change well before departure, to ensure that the fuel flow from the last-selected tank is "proved good" before takeoff.
If for some reason you have forgotten to change tanks during preflight, it is safer to depart that way, and change them when at a safe altitude and over some fields
I also don't change tanks in flight when over water.
The issue is not just fuel; you can introduce a lot of water into the engine, if the aircraft owner has not bothered to keep the filler cap o-ring seals in a good condition, and there has been heavy rain. This is a very common problem. I have not seen a single drop of water in 9 years in mine, so "condensation" is not the reason for water in tanks.