I have two dogs, a 5yr old beagle min pin mix and a 18yr old english setter. They are both very active dogs but louis the setter is settling down with age.
I regularly leave them alone for 12-15 hr days without any problems. The only accidents they have had where when they are sick. They are happy too see me after a long day and ready to go out, but it doesnt seem to bother my dogs.
I rescued a kitten about 8 months ago and it plays with my dogs like they are best freinds. I think this helps to burn energy off when Im not around.
If I am not working my dogs are with me 24/7 to balence out the time I spend away. I take them almost everywhere I go and they are perfectly content waiting in the car while Im shopping.
I think it depends on the dog but I think it is doable especially if you can go home at lunch for the training stages.