When the tape is good invention for band-aid, it is only as good as preparation job and lot of not only amateurs, but also professionals lack in this part.
PO of my Fleetwood used it a lot to patch branch-inflicted holes and the main issue is that without proper preparation the tape leaked, but also hid the leaks till frame started to collapse.
About a year ago Home Depot started to sell new-technology white roof sealer and I had it applied last spring on my house flat roof. Impressed with the results, I plan to use it on my camper rubber roof as well. Price is about $50/gallon, but that can save you lot of money and aggravation on long run.
The brush-on or rolled sealer not only is very good, but making even surface - you will spot any crack right away.