I once was in line at the CZM kiosks for more than two hours (longer than we were in the air from Houston) when four planes landed within a very short period of time. I was on plane #3. When I got to the line the serpentine waiting area was full and there were two more unroped loops inside and then out the door. When I first arrived there were only two open windows in Immigration, although after an hour or so they opened one more.The longest wait I have ever had in CZM was about 45 minutes. High season Saturday with three plane loads and only 2 1/2 of the 5 immagration posts manned. Similar occurrence in CUN this winter with a 1 1/2 hour delay and again the delay was due to staffing the immagration posts. The government actually put out a press release after the CUN incident apologizing and promising to better manage staffing in the future.
I'm pretty sure weather delays made the plane arrivals stack up more than they anticipated.