I think what they're saying is that they could book FP+ #4 for 30 minutes from "now". For example, if they tap into FP+ #3 at 2:00pm, the next available FP+ they could find was 2:30pm-3:30pm...or later. That is often the case, but if you don't mind doing a lot of refreshing on
MDE, you can very often make that only 10-20 minutes...or even less.
Like I mentioned before, on a "good" day, we can go through our first 3 FP+ in about an hour or so. For example, say we have FP+ 9-10, 10-11 and 11-12. We show up at 9:40am and go right to FP+ #1. By time we get off, it's nearly 10am anyway, so we go right to FP+ #2. As soon as I tap in, I'll jump on MDE and move FP+ #3 from the originally scheduled 11-12 to something like 10:15-11:15. That way, as soon as we get off ride #2, it's time for FP+ #3. When I tap into FP+ #3, I start looking for #4...and with some playing around I can usually get it for a short amount of time away. Rinse and repeat...
The best example I give people in these threads is last Xmas. Busiest week of the year. We were in MK. As a 4th, 5th, whatever (I wasn't counting) FP+ I found our kids Space Mountain for something like 15 minutes from "now". I also got Pooh for DW and I (I love Space, but DW won't ride it, so I wanted to stay with her). We got done before they did, so we were hanging out in the Space gift shop. I was playing on MDE and wound up finding another Space FP+ for 5 minutes from "now". So as soon as our kids got off Space, they turned around and went right back on. No guarantees at all that you will be able to do that, some of that was luck for sure, but the point is that you can often grab FP+ pretty quick.