What are the maximum limits for allowing wot downshifts that are safe for the transmission?

For example:

6200rpm shift points say the car shifts to 3rd at 90mph, but it won't downshift to 2nd above 65mph...is there a limit in the gap between 65 and 90 that is acceptable? Obviously you don't want it to downshift then upshift immediately...but much better can you make it before you're risking issues?

Or is it better to just manually pull the car down at cruise or lower throttle input then go WOT once the downshift is complete?