if ballots start becoming too long, they may want to propose separating the Main election with the secondary seats, or whatever the other category is. It doesn't really make much sense to have everything all in one go anyway. The last thing we want is for voters to find that it's too much of a timecrunch to do. if it's taking 35 minutes to do a ballot then the ballot is far too long. Voting should take 5 to 10 minutes tops, anything more means there is too much information for someone to absorb in the first place which means it needs to be isolated.
With my mail-in ballot I had to spread it out over the course of two days, and that’s with skipping the judges section. I can’t imagine going and voting in-person without either skipping 75% of the ballot or researching beforehand and coming in with a cheat sheet.
Unless you are intimately familiar with your entire world of politics, I would expect you (and everyone else) to spend a little time researching them all. Depending on how many contested races there are and how nuanced your votes, this could take between an hour and a week.
Countless people bring their cheat sheet (mine was officially called "literature" when I voted recently, despite just being a sample ballot I had filled out). Both parties hand out a professionally printed version right outside polling places.