I have a Crealock 37 and sail singlehanded 99% of the time. My stay is permanent.
A staysail is all about balancing and center of power for your boat.
I love my staysail and find it's my most useful sail especially as a singlehander. Great for helping to balance and power with or without my monitor windvane.
Use upwind, downwind, light winds and heavy winds
Use instead of partial furling jib in heavy winds
Use in conjunction with my aso
Use when heaving-to
Use only stay when a chubasco or elephante is on the horizon, etc.
Never had the need for the storm sail or para-sea anchor that came with my boat...Hawaii & Mexico vet. Always check the forecasts and avoid the need...storms are no bueno for me
Read about staysail use but you'll only learn how cool/useful a staysail is with experience...
Go sailing, go sailing often. Sail with main & stay only upwind, downwind, beam, light and heavy wind, etc.
Practice heaving to, practice balancing boat with main and stay, then practice balancing with main, stay & jib.
Go sailing, go sailing often!
That last thing---A staysail looks so cool!