I don't do 35 hours regularly, TD. In fact I've only exceeded 30 hours a handful of times in the last couple of years, invariably influence by bonus chasing. My average would be closer to 20 hours/week taking holidays, lazy months, etc into account.
However, I wouldn't consider 35 hours to be excessive. Most full time employees do that as a minimum and spend another few hours commuting. Of course, it's not an exact science. While I might feel tired after a relatively short shift, a younger fitter man would be capable of doing the same again and hitting a disco bar afterwards!