BB's are sealed these days, - i.e cartridge or outboard...and have been for years..... One of my bikes has cut outs on the BB shell for water..why ? as my best bike hasn't and has been water tight for 18 years....
The new carbon bikes might collect water, but the BB's are out of this issue as sealed and not prone to rust..... like the old bikes I have....water near seat pin isn't good.
Parking the bike in particular gears..rubbish... my best bike is 18 years old, running original DA equipment, and is parked in the gear I get home in.....