So to get another data point, I looked at another attraction that got FP fairly recently right before the pandemic - Millenium Falcon. Falcon got FP+ added to it on February 19, 2020. I looked at the Crowd level 10 days before and immediately after FP was added using Touring Plans data, as they were all listed as crowd level 10 days at DHS (except 2/21, which I took out of the equation). So I measured 2/15-2/18, and then 2/19, 2/20, 2/22, and 2/23. Granted the full sample size for MF on FP+ is very small due to Covid shutting everything down, but it does present an interesting case study. All dates had MF at 100% capacity (no downtime to skew the results).
The standby line increased by an average of 11.5 minutes between the before and after days - right in line with what we saw with Pooh, HM, etc. back in 2014. So a small increase overall in standby wait times, but not substantial.
Other things can also be factors, such as other attractions being down, the fact that CL10 has a very wide range in TouringPlans' model, etc... (For example, I also picked 4 CL10 days in January and came up with an average of 116 minutes, which means if I had done that comparison, FP+ would have resulted in a 2.5 minute shorter standby line). This is also a *very* small sample size, so it should be taken with a grain of salt. It would have been better if we had several months of FP+ data so we could weed out any initial operational challenges, etc. that may have occured with the start of FP+ at Falcon.
What I think this shows though is that there is some data to say that while FP+ *may* result in longer lines (and no data exists to show that it actually results in significantly longer lines that anyone has been able to show me), it doesn't result in *appreciably* longer lines.
Pre-FP Avg daily wait time:
2/15: 99
2/16: 112
2/17: 97
2/18: 100
Avg: 102 minutes
Post-FP Avg Daily wait time:
2/19: 116
2/20: 120
2/22: 106
2/23: 112
Avg: 113.5 minutes