Nope, but that is what I used to think also, the vacuum should be highest at idle.
A lean fuel charge burns slower so you need more spark advance, which is what happens when you have a lot of vacuum.
THere is no vacuum advance at WOT only at idle or cruising.
There is zero vacuum at idle on a ported vacuum inlet. Only when the throttle blades are cracked open or at cruise. Vacuum drops off on sudden acceleration, or WOT.