Don't think about it, just do the memory drill ! DO NOT INVENT YOUR OWN PROCEDURES.
For example, as many have said, raising the gear adds drag, and moving any hydraulic item such as gear or flaps puts extra load on the engine driving the hyd pump.
Lots of folk at the manufacturers have spent time working out what is best to do in any situation, and their test pilots have flown each procedure and refined it so that the average line pilot can fly it safely.
As many have said, ask the instructor to show you where in the company or aircraft manuals what s/he says is written down. Or ask your chief instructor to clarify the procedure and when they ask you why, tell them what you were told and by whom.