I know a lot of people put bigger conventional refillable tanks on them via a hose. And, I know some people refill the "non refillable" small bottle from a conventional legitimately refillable tank.
I've never been willing to refill them because they can go ka-boom and clearly warn against it. But, again, others do.
I've never put a bigger tank on it because I don't want to mess with putting in a chain locker for it. In general, I just don't use it often enough.
If I'm making the occasional trip to the boat and cooking out on Sunday afternoons, it can last me 1-2 months, depending upon what I cook and how. Ditto for week long cruises or the occasional longer one. I'm never far from being able to buy more.
The longest I've ever lived aboard continuously was 18 months. The next longest continuous stretch about 2-3 months. Over those periods of time, there were phases where I seemed to be going through bottles like water cooking for me every night and neighbors sometimes, etc, and sometimes when I was on a grilling kick. But, I usually settle in to a mix of outdoor grilling, eating out, quick stovetop meals, slow cooked meals, and baked meats + stove top sides.
In those modes, the added cost has been outweighed by the convenience.
I usually marina or mooring hop vs anchor out and have a generator and electric indoor cooking, so I have a lot of options and tend to use them all vs just grilling.
So, I guess my answer is that, if I used it every day, I'd put in a locker and big tank. But, for what I do, I pay the piper to minimize the gas aboard.
