I can't say I am going to find a massive problem with the small wait, but, I do see a bit of a problem, if you are from somewhere where the choices are not familiar. Like, we had refillable mugs last time, and loved them, but, the first time, we wanted to try the things we didn't recognise (cos, you know, it's endlessly refillable, we can try one, not like it and just get a different thing, not like committing to a whole cup of something)
So, we tried a small bit of the root beer, and the lemonade, one we did;t like, one we did, but, had they had the timers, we would have to have remembered to wait three minutes or whatever, to get something different, or to top up the mug having discovered we liked...
It's not a big deal, but I can see me forgetting...