It's not about having 400 amps per se but about sizing the wire you put in the ground. Maybe you'll have a 200a main breaker and you'll only ever use 200 amps, etc. - but the hard part was digging and future you or other future yous will be happy that the wire was upsized when it was put in.
Same with conduit. Same with number of conduits.
I can't tell you how many times I have been very pleased with myself that I threw in that extra 3/4 conduit line when we dug that one trench that one time ...
It's not about having 400 amps per se but about sizing the wire you put in the ground. Maybe you'll have a 200a main breaker and you'll only ever use 200 amps, etc. - but the hard part was digging and future you or other future yous will be happy that the wire was upsized when it was put in.
Same with conduit. Same with number of conduits.
I can't tell you how many times I have been very pleased with myself that I threw in that extra 3/4 conduit line when we dug that one trench that one time ...