If I’m reading this right, and I like to think I am, they’re going to have 24h of argument from each side, 16h of questioning, THEN a debate about witnesses, and ONLY AFTER THAT are they going to decide what documentary evidence is admissible in the trial.
The typical procedures used in US courts seek to resolve broad, categorical questions about what is admissible evidence before the trial begins, because that obviously shapes what arguments can be properly made.
McConnell’s proposal inverts the typical procedures with some bizarre effects. First and foremost, the advocates would be arguing and being questioned by the senate in the absence of any official record. Unclear what they’d say or be allowed to cite and refer to.
Second, to the extent there are witnesses, their depositions and testimony would come after all the argument/questioning. The advocates wouldn’t have the benefit of that testimony in their arguments. And the process would insert several weeks between arguments and deliberations.
Third, without any evidentiary decisions in advance, the public may hear a lot of argument in the form “evidence will show that Hunter/Joe Biden...” from the President’s advocates and then wait several days or weeks before the Senate votes on its relevance.
Remember, McConnell described himself last month as “taking my cues” from the White House in shaping the trial. He swore an oath last week to do “impartial justice.” Then he promulgated these proposed trial rules tonight. nytimes.com/2019/12/13/us/…
For comparison’s sake, here are the 1999 Clinton trial rules, in which the whole House record was admitted into evidence upfront. I’d point people in particular the these two sentences in relation to the points above. archive.nytimes.com/www.nytimes.co… 
