Is your question how much time does it take? Or is it how much energy does it take?

If your question is the latter, then Mino 15 gives an average of 28 small, 13.5 medium, and 9 large scrolls. You need a total of 100/600/950 scrolls. That means you need an average of 153 runs per champ to get full masteries. For four champs, that translates into about 614 runs.

If the question is the former, then assuming we take only the daily 50ish autobattles you get, and assuming you take 4 minutes per clear, it'll take you about 12 days worth of autobattles and about 41 hours of game time. 

Also, to be clear - if you aren't leveling those four other champs at the same time as getting masteries for them, the benefit of farming scrolls is significantly diminished. If you're using five level 60s, you're going to spend quite a lot of energy that you could have used for gear farming. At that point I'd probably recommend using gems instead.

If, however, you're leveling those four, then you can take them from 5-star level 1 to 6-star level 57 while maxing them on scrolls.

Lastly, four minutes is *really* slow. When I was doing it with BEK, I'd average around a minute and a half. Even when I was using Ignatius, I was still getting two and a half minutes. I expect there are plenty of champs you have that should be able to farm faster. Remember, getting the rest of your team to die speeds things up quite a lot.

I cant see your roster, but one thing for sure, you can use Artak to solo Mino + 4 other champions. 

Depending on who you bring in to level up, Between 1:30 and 2:30 per run. I'm saying this cuz some champions are totally horrible at dying and just end up slowing the run down. Revivers, Block damage, Unkillable, Strengthen, increase defense, those types of buffs stop your naked champions from dying fast. The fastest runs will be if you bring along nukers and/or debuffers.

But generally speaking, just bring them in naked. The faster they die, the faster your main champion starts stacking extra speed and extra damage.

Locked to prevent post editing for further spam links. OP, I'd check your system with some sort of antivirus.