They are probably the biggest, best known insurer and have an excellent record, at least in my mind, for efficiently handling claims. In some circumstances there may be reasons to use others, but there is no reason not to use them.
How much time one needs is wholly dependent of the location and circumstances in which one operates, as well as one's natural talent and demeanor.
My first boat was a 42' trawler and they wouldnt insure me because I literally had no experience on the water, "Don't fit our risk profile". They gave me no option for training. I ended up going with State Farm that insures the rest of my world.
I started out at Absolute Zero single handing a 42' trawler around Los Angeles harbor. I made a brief attempt to hire a captain to teach me. The first was with a not-so functioning drunk. The second was with an excellent boat handler -- who wantes to exhibition, not teach. 3 hours and $300 wasted.
I probably had about 50 hours the first time I went from LA to Catalina, my first real cruise -- at night in 10ft (west coast) seas during a small craft advisory. I had 4 passengers, one of whom was an excellent and experienced deckhand (grabbing mooring ball, etc). There wasn't a tense, confused, or white knuckle moment.
I had less than 100 hours of helm time the first time I made the crossing in 100% fog (which neither included Avalon or the LA Harbor, but included nearly all of the channel. It was a long, slow crossing 100% on radar and AIS. A lot more was white than knuckles.
Early on, 5he only moments where I had real trouble were while returning to the slip. To this day, bad cross wind/current gives me trouble -- I just to wait it out if I need to.
Early on, I probably had 4-5 /really/ bad days getting back in before mostly figuring it out. One day I got blown past my slip thrice, ended up at an angle to the slips from which I couldn't recover, got blown to the side dock and backed into an empty slip there. On another day this 70-something year old neighbor came running to help and got pulled in as the wind got control of the boat when I should have had it (he was a trooper, saved himself, and dripping wet on dock in slacks and a button-down shirt secured the rope and then helped me ease in).
And, yet, now that I'm in Florida with a ton more helm time, I won't go out very far from my home matina at night without locals aboard, or go out during bad weather, etc. The shallower water makes for squarer waves that are beaters, narrow channels bounded by shallow water and crab traps allow little room for error, and entries to matina areas are often "passes" with approaches that look like a Christmas trees of lights and waters shallow enough to walk away from an errant boat.
I hate to admit it, but recently I soft grounded myself exploring a bayou off of a river (I wiggled out very quickly) while some guy on land yelled at me, "You need to get some more helm time before taking that out!". How does that even make sense? I knew what I was doing had some risk of finding bottom. I went slowly enough to get back out. Since then locals have let me know that bayou isnt for my boat, except along an uncharted path, at the right tide, until the next big storm changes it up.
My point isn't that one doesnt need instruction -- one does. My only point is that one probably doesnt need to have 50 hours of instruction to enjoy safe boating in many common circumstances. By the time I had 50 hours of helm time, I had a ton of fun -- getting 50 hours of helm time.
