Along with Nigels comment that regular opening and closing is good exercise for the seacocks keeping them fit for use with nothing clogging them up. It is good for all crewmembers to know where they are located, if never really operated the will never really be found at a time of dire need.
Also a bilge
visit opens your eyes to ensuing problems, one thing hose has a habit of doing is working loose over time due to thermal changes, first hint is a rusty dribble indicating a screwdriver is needed.
If there are concerns of forgetting to re-open them put the engine start keys on the main seacock.....