It depends completely on the boat and where you are sailing. And while some people manage to do it, it is really hard to make one headsail that works for all conditions.

Hawk is a big main/small jib fractional rig, and the 105 is almost perfect. Easy to tack and jybe and enough power for 12kts apparent and above. But it is underpowered under 12kts and we had a real hole in our inventory until the code zero was perfected. With the zero we essentially have the 105 on the main furler and a 150 (the zero) on a second removable furler.

On Silk, we had a short rig ketch and she needed a 120 on the furler to be powered up, but then there was a real hole in strongish conditions - too strong for the 120 but still too light for the staysail. Shannon solved that problem with a second headstay that took hank-on headsails and we kept a 90% yankee hanked on which filled that hole.

Inshore a bigger jib tends to be correct because most people don't choose to go out in strong winds, but if you are going offshore a smaller jib is usually correct because then you don't have any choice but to sail in stronger winds.

If you are in S Calif (where they think a #2 is a storm jib) a big jib makes more sense than if you are in Newfoundland.

So, our sense is that to sail well in all conditions you really need a minimum of three headsails (a big light air one, a 'working' one and a storm/staysail one). If you are only doing day sailing, and only go out on 'nice' days, you can do with one biggish light air one and use it partially furled in somewhat stronger conditions.

We do have two friends (john Neil and Webb Chiles) who manage many many miles with a very small headsail inventory. John has a dacron 120 on his furler and just sails with it partially rolled in stronger winds. He has a staysail/storm jib but says he has only needed it 3 times in something like +250k miles. Webb has I believe a slightly smaller headsail (a 110 I think) on his furler and uses it for everything and (I believe) not even a storm jib.