It actually is easy and works pretty well. We look and see what is available that we want and as soon as we tap for that third FP we click on a 4th one. If it’s not the time you want, refresh the page over and over. And often more times will appear. As soon as you use that fourth one.... keep repeating and refreshing. If you ever end up with one you decide you don’t want, go to the attraction and just tap on it so you can more on to a new one. If you decide to leave the park for a break, as soon as you do the last FP at that park, add one for whatever park you will visit later in the day. Also keep an eye on your FP app, sometimes you will get a bit of magic and an extra FP will appear. Also watch in case one of your FP ride is down, you may be offered an any attraction FP. Sometimes it will exclude a few high choice attractions but not always. We rope drop every park and schedule FP for 10-11=12,moving them up as we can.