I understand the concept, but I just didn't see that kind of availability. Cancelling your passes is only going to give you a small chance of getting Rat.
Mind, I'm aware of the strategy because it dates back to the days of FP+, and in the last years of FP+, it worked with FP+. With LOTS of refreshing, I was able to get more than 1 FP per hour, and able to get the big rides. I just had to have my phone out all day. (Through every queue, I was refreshing. While I ate lunch, I was refreshing. Between rides, I was refreshing. Making it work required a trade-off.)
In the early days of FP+, refreshing wasn't even an option. the only way to modify a pass once you were in the park was to use a kiosk. It only worked with much-later FP+.
G+ inventory also improved over time. Initially, modifying passes was not an option. Users had to cancel to rebook, and that was risky. I experimented, and had little luck. Later, it got much easier to modify G+ passes, and refreshing worked pretty well.
I'm fully open to the idea of using the no-prebooks/refreshing to get passes. I have been careful - I think - to qualify my posts by saying, 'this was my experience' and 'for now.'
WDW has a history of sharply limiting the total LL/FP inventory when they roll out a new version of their express pass. I can't say that will improve, but given the history, it probably will.
It is also important to add, IME, this strategy tends to work much better on slower days than during busier holiday weeks.
