well, i don't know shit, but i was once voir dired for a federal case here as a jury member. i've also been voir dired (and chosen) as a travis county juror. i've also stood in travis county court as a defendant more than one time and once spent a night in the building as a guest. i've also testified as a witness in a murder trial. so those are my non-lawdog bona fides, ymmv.
the federal case was a humdinger - it was the relatively open and shut case of the guy who shot judge kocurek. nevertheless, i had to fill out something like a 30 page questionnaire before even showing up for jury duty. there must have been some 150+ of us in the pool. and most of us faced some form of question from either the defense or the prosecution. it took pretty much three whole days. this was for one defendent, in a fairly complicated case, because the shooting was really only a minor part of a larger racketeering thing. i was not selected for the jury, in part, because my voir dire had to do with my being a witness in a murder trial, and whether i would just rather "not go through that again" or whatever. pretty sure that was disqualifying for me in that one. anyways, as i recall, that trial took months. they found him guilty, but not of attempted murder - it was all the racketeering, which was also a big part of our questionnaire (have you ever had your identity stolen, etc).
the county case was also a humdinger - super aggravated sexual assault of a minor. prior to showing up, i also received a lengthy (probably 10 page) questionnaire. the jury pool was pretty big, i'm told, and there was maybe 100 of us? jury selection took all day, and at the end of that day i was selected as a juror. we found the guy guilty, and he's gone away for awhile. this trial took us four days.
both of those trials were kind of big local prosecutions, so i imagine my experience was vastly different from most jurors. we had a talk about how to handle journalists in both cases if contacted. neither obviously involved the former president of the united states of america and his many lawyers who also are accused of breaking the law.
i can't imagine how long it would take for jury selection in such a trial - the number of questions asked pre-selection, and the follow ups necessary during selection, for 19 different defendants? impossible. this isn't a mafia trial of some mob bosses in a huge racket.
or is it? i don't really know.