i understand the leg thing because on 3 day workouts you cant dedicate a full workout to your legs, so there has to be some comprimise.

I see what your saying but the same applies imo greater to the groups i showed. The biceps and triceps are an antagonistic muscle group (grouped together and work appose to eachother) so this is the most logical grouping of any muscle groups and seems to be the kind of thing you p.t is on about. But as i always state, theres no standardized way to have a weight routine so im in no way saying your P.T has designed you a swrong routine