Like I said, 60-80 songs per event.
Subtract from that client requests that you already know about pre-event.
Subtract from that top tracks that you already plan on playing.
When it gets right down to it, how many requests can you realistically accept within that time frame that you will have a reasonable chance of playing anyways???
Like I also said, if the track is that good you should already have it and have planned on how you are going to incorporate it into the playlist.
If it's a new and emerging track you don't know about that someone requests and may be available on a streaming service, simply take the request but tell them that you already have too many requests and it's not likely that you will have time to play it. Since you don't know the track you also have to take the time to listen to it (and for more than 30 seconds) to make sure it's going to not only fit the flow of the event but not contain overly explicit language or innuendos (odds are it will, given the majority of today's crap).
Do you really want to take your focus off of the event for that time period to perform those safeguarding tasks?
No, you note the track and play it later at your convenience and decide then if it's a track worth keeping.
As I and
@ittigger already mentioned, allowing the guests that much instantaneous power and leeway does not make you "in touch" it only opens you up for self-sabotage.