I learned a very important lesson in the past ten days.
Our pretty Beneteau 473 sailboat came complete with all of the options, which means lots of convenience, and more things to break.
Last week when we sailed south from Current Cut to Hatchet Bay, we had all the sails up, and enjoyed a great ride south. Before entering Hatchet Bay, we lowered the sails (which is normal), and motored into the bay, got a free mooring ball and relaxed.
Unknown to myself there was a very serious and dangerous problem which went completely undetected.
After a day of heavy winds, the main (large) sail had suffered a failure, and the loop at the top of the sail to which the halyard (rope) is attached had failed. As I "lowered" the sail (our main sail is a mast reefing sail which means I roll it up inside the mast) I used the normal large electric winches (Lewmar 58s) and with the sail sagging due to the broken loop, we wound in the sail into the inside of the mast imperfectly.
The result was the next day, we motored out of the anchor, unfurled the genoa, set our course, then unfurled the mainsail.
Three quarters of the way out, the main sail became completely jammed inside the mast... couldn't pull it out, couldn't pull it in, couldn't lower it, completely jammed!
Thankfully the winds were light, so while under sail, up the mast I go... rather exciting being 60' above the deck swinging from a rope, attempting to unjam the mess inside the mast.... no halyard to raise things...

After a couple of painful hours I succeeded in unjamming the mainsail, so we could pull it down by hand and strap it to the deck before our arrival in Governor's harbour. In serious weather it would have been a nightmare!
Another four hours up the mast fixing things, sewing on a new loop using part of my scuba weight belt, re-hoist the mainsail, and roll it properly back into the mast.

I am not sure furling mainsails inside the mast is a good idea. When things get stuck, you have a potentially deadly situation.
Lesson learned!