Sure, but depending on the strength of the genjutsu it isn't quite as simple. Someone like Jiraiya using a sage-level sound genjutsu doesn't seem as tho a simple tap on the shoulder would be enough to cancel it. Obviously this is evident in situations like Itachi's tsukoyomi. (how close am I to spelling it right? cant believe I even remembered the name of it) where people get trapped in it for days regardless of outside interaction.
I think the whole rinnengan counters sharingan is more due to sharingan being the perfect reaction based bloodline technique. But its obviously more difficult to react to multiple targets. Especially ones that use techniques like the Yahiko Pain used, there's nothing to really analyze with the sharingan... the only thing to notice is the time it takes to recharge and that is evident with or without the sharingan.