so, leeneia, approximately the same number of electronic tuners as there were pairs of ears - no great numerical advantage either way.
But yes problems can and do arise when a person who is a strong (read "loud") player is slightly out of tune, even if only one string is off the difference can be confusing, especially to fiddles and voices. The only way out of this is to wait for the end of the set and ask for an A (or whatever). Usually everyone will feel a bit guilty and check their tuning.
As a youngster I was shown how to press the scroll or tuning peg to my ear so I could check my tuning while the rest of the orchestra were playing, I imagine this trick could apply to all stringed instruments.
But I repeat - it essential to tune to the instrument whose pitch cannot be (easily) adjusted, rather than a (theoretically correct) pitch standard that one of your group is incapable of tuning to.