I think your original question has been answered well by those above. I’ll just add that in my experience, bilge systems tend to deteriorate without use. In a wet boat, everything gets a bit of exercise, lubrication. In a really dry boat any moisture which gets into the bilge dries up to leave salt or lime scale. Residual oil causes gaskets to perish and rubber parts to harden over time.
When you maintain a lifeboat, it’s part of the regular scheduled work to flood each compartment until the bilge pump kicks in. The failure rate for float switches is extremely high.
If you keep your bilge clean of fuel, oil or diesel, then you can get them even cleaner with a good flush out with fresh water. You cannot afford to have your bilge pump fail, and unlike a liferaft, flare, or hydrostatic release, you can test it any time you want. I do mine twice a season.
Alternatively, if you never replace the packing in your stern gland*, your boat will leak just enough to keep the bilge system in regular use.
*do not do this