I was in the 40’s and it wouldn’t let me go to the next one because it said my gear was too low so I reset. I will be back up to 50 today.
Ah right it does that sometimes I forgot how it works been so long since I did it the first time and my new account doesn't have HW so I can't do potd(well can't do it past 40, so might as well not do it at all).
It might be more than 1 run though it's been a while, might be 2. I think it switches to 3runs per lvl around, 43 or so? But the runs are pretty fast. Squadrons might be faster too I'm not sure I never used these and don't have a class that can use them on my main account.
I found leveling all classes to be fairly easy and relaxed though, but it gets grindy if you're trying to dump 6hours into it in a row. It was posted before but the "right" way is to just do your daily leveling roulette on even levels, then queue for the new dungeon on odd levels(in ARR the dungeons aren't every other level though so that works a bit differently), while you do beastmen tribes and daily bounty hunts(the HW/SB ones, the ARR ones are shit) while waiting for the queue to pop. Can also do trial roulette, pre50 there's hunting log too. Basically you do this stuff takes like, 2-2.5 hours, that's 2 levels, and then you do something else like expert roulette on your main, some crafting whatever, and just do that everyday for a while. Can mix in sidequests/fates while waiting on queues if you want to do a 3rd level.
It's definitely not super fast to level alts, but it's relatively simple and you can get side content done at the same time(beast tribes especially). Worst case you just do leveling roulette for 1 level a day, takes like 20mins and you're done. Obviously this will take a while to get all classes to cap, but a lot of people opt for something like that, very low time investment, good if you have stuff to do on your main too and not much time to play and you're leveling alts just for the sake of leveling them rather than for rerolling. It's like how you can level all your crafts to cap just doing ixal/moogle/namazu daillies+GC delivery turn ins which takes like an hour to do on all classes and gets you like 30% of a level on everything + 30% on the class that does the beastmen daillies, and eventually you have everything capped without having spent much time or effort into it.