All depends on the boat. PO told us our boat, a Pearson P30, can handle a 150 genoa nicely up to 20 kts or so, IIRC. As proof: Boat comes with the original main, jib and genoa (all in good condition), and a new main, light 150 and heavy 150. He didn't bother with a new jib, much less a storm jib.
Oh, and two spins, which, someday, we hope to learn to fly