It depends on your goal. I think 400mg with whatever else you are running is more than enough to raise free test and do all it's water-shedding magic. But again, it depends on the look you're after. The only "fitness model" I've talked pretty in depth with about this is Jon Skywalker who swears by Masteron higher than Test. He switches his stuff around so much but his go to was always about 250 test and 400 Mast. I haven't talked to him in like a year but that's basically what he cruised on, I believe he's toying with tren a lot more now but I'm not sure.
That's just one guy though, but keeping androgens high and aromatizing compounds low seems to be very big among the "aesthetic look" crowd. It seems to be the opposite among those more serious about mass but still wanting to keep water retention down.