Waterfall displays are useful in assessing a target frequency's short-term history of signal strength and activity.  For sought after DXpedition signals working split and calling "5-10 up", I can often identify a sweet spot of lower activity within that range to make a call, improving my chance of a successful contact.  Here is an Elecraft perspective on Panadapters and their utility  https://www.hamradioworkbench.com/podcast/panadapters

KM4KMU here.

For VHF/UHF work I find the waterfall display to be a bit of disadvantage.  A waterfall makes it easy to find big powerful stations but you can do that with or without it.  The big stations get worked early.  As the contest wears on or e-skip is weak or not present the waterfall display doesn't show the weak stations that either don't register or are so intermittent that you have to work them really hard to dig out the call and grid letter by letter and number by number sometimes over and over to get a QSL.  You think that want to jump from one waterfall registered contact to another to make it fast and easy to rack up the QSO count but in reality by letting the waterfall steer you around the bands you end up missing smaller weak stations that you would otherwise find by slowly tuning kHz by kHz up and down the bands.  Many are hidden near or even underneath the big traces if they show up at all.

Honestly I like having the waterfall to see the easy catches when the band opens but I have to fight the urge to become a slave to it.  Ideally the big dogs run and stay put on a freq (which you remember) and when its time to shift from running to S&P its the knob that finds the hidden jewels.

73, John, KM4KMU