I use 3 different A&H desks, all analogue.
I have a really good set up on one of the desks and we sometimes vary the delay length, using the 'tap' button, it gets the delay in time with the song
I started with a preset and then fiddled with the available parameters.
I really like how my most used desk sounds and need to see what I've done and copy it to the other desks.
If I was to go digital, I would probably try and set it up similar to my main desk. I don't seem to hear any need to change anything from venue to venue but with the digital desk you could probably set each singer up with what they want to hear, in the monitors or not. With my A&H desks it's everyone gets the FX or no one.