So, currently, in the Sydney commercial brewing scene, there is debate amongst brewers about mashing out. I'm not gonna name names, but there is one HUGE brewery that doesn't, and the rest of us are like, wtf? But I guess if you know your process that is all that matters.
My opinion?
I mash out always on the grainfather, or commercially, never with BIAB.
When I mash out on the grainfather, I do 10 mins at 78, whatever that is in C. (I'm American, but refuse to go back to Imperial lol)
I'm with whomever said the entire grainbed won't be 78. I go to 78, set a timer for 10 mins, and lock in the flavour profile. It also helps with efficiency IMO.
And with step mashing, I don't really do it, but if we're making a classic style (we just made an amazing Märzen) we step mash
Also, with classic styles like Märzens, the colour actually comes from a long boil, not a crystal adjunct malt.