If I'm running an implement on one of the PTOs I always set the pto rpm to the implements' working rpm. Rear pto usually 540 rpm, which is near 2,400 rpm engine rpm.
The only pto implement not run near engine rated rpm is the post hole auger. Spins around 300 rpm.
The front pto mounted snow blower I run at 2500 rpm, my tractor's "rated" working rpm.
I NEVER operate the engine at WOT. It governs out at around 2800 rpm, but I always set it near THE 2500 RATED rpm for heavy work or pto work. In my way of thinking WOT IS NOT THE SAME AS OPERATING RPM.
WOT simply makes the governor cut in to keep the rpm within safe limits. It isn't the correct working rpm, too high, and likely hard on the machine to keep working it with he throttle lever slammed down.
When I'm busy with loader, forks, box blade, etc (no pto involved) my engine rpm ranges from about 1800 - 2200 rpm. It's not really needed to go at 2500 rpm to work efficiently, puts out plenty of power, and it's a lot quieter too.