I also tried Flex Seal spray and liquid and found it leaked right away and did not last long. Since I only needed 2 feet and it comes in 5 foot rolls at Walmart I did test the Flex Seal tape on my shop roof which is metal paneling. It has lasted 3 years so far with no signs of deterioration yet. It seams to be a thinner version of Eternabond which is just as sticky but I don't expect it to last as long. So maybe the only reason to buy a small roll is for emergency repairs on the road.
When I bought my last Class C six years ago I did the entire roof using over 100 feet of Eternabond and 3 1/2 gallons of Liquid Roof. At my age I'm thinking I'll never have to worry about the roof again. For 40 years on my previous RV's and 14x80 vacation mobile home I applied roof coatings and caulking every few years. With mixed results and several days removing the old caulking every time. I'll check myself into a mental hospital before I decide to go that route again.
When I bought my last Class C six years ago I did the entire roof using over 100 feet of Eternabond and 3 1/2 gallons of Liquid Roof. At my age I'm thinking I'll never have to worry about the roof again. For 40 years on my previous RV's and 14x80 vacation mobile home I applied roof coatings and caulking every few years. With mixed results and several days removing the old caulking every time. I'll check myself into a mental hospital before I decide to go that route again.