Because there's no need to hurry. A week is more than enough to do all the relevant weeklies. Subs can be easily repaired during daytime, and the damage to other ships can be repaired during night easily using 4 docks + 1 akashi in the main fleet. If not, just use a different ship which is not damaged yet. If you follow the schedule well, you'll be done with weeklies before the weekend anyways and can use it to let repair any other damaged ships you were not using atm. No need to waste precious stock-colle resources just for repairing.