I think that it's manageable, esp. if you are doing breaks for meals/exercise/etc. and getting enough sleep, even moreso if this is not an every day of the week

I think that it's manageable, esp. if you are doing breaks for meals/exercise/etc. and getting enough sleep, even moreso if this is not an every day of the week plan (two days on, one or more off, for instance). Without any data on frequency or what this person is working on, you really can't make a blanket statement like that.