Something that always bugs me is getting an opponent that I guess is multi-tasking or watching tv in another room while playing magic arena. The person that takes 30-40 seconds to play a land and maybe a one drop. I would love rope timers that gradually increase. Something along the lines of:

Deciding Mulligan: 10-15 seconds Turn 1 - 5 seconds. Turn 2 - 10 seconds. Turn 3 on - go back to the normal time restraints, or add 10 seconds per turn until you reach the current max.

IMO turn 1-2 should fly by with minimal decision making. In real life they maybe take 20 seconds for both of us to slam down our first two lands and maybe a card or two. Yet in arena having an opponent hit the rope timer in turn one or two is so aggravating.

The other option is to get a 5-7 minute chess clock in BO1. That way I don't care if my opponent takes 2 minutes to Mulligan and play a llanowar elf, they're going to really have to pick up the pace to finish the game in their allotted clock.