The fact that it violates Senate rules for any electronics on the floor.
But who the fuck cares about the rules at this point, 21 Senators bailed tonight while the Senate was in session. My guess is they needed to take a Schiff.
Prosecution gets until end of day Friday to lay out their case. Defense would start either late Friday night or Saturday morning. I think they skip Sunday and pick it up on Monday and Tuesday, at which point it goes into question & answer period, which is two 8 hour days.
After that it's up in the air because the question of witnesses and other topics come up for a vote.