Some days the dogs are great, having fun, doing well, and the training session can easily go an hour. But it isn't a full hour of training because I pause for play. So you could say I train for 10 or 15 minutes at a stretch.
Then there are those days when absolutely nothing is working, the dogs have forgotten their names, or think catching grasshoppers is much more interesting (Bonnie), or have decided to dig for mice (Joey), and can't settle down and focus. In that case, I forget all about training and just throw a ball around and play a bit to exercise them and blow off some of that teenager energy.
Or you could say that we're almost constantly in training, except that it's the dogs trying to train me! They're pretty good at it, too.
Hmmm. Sort of varied. Because she's still a pup, they're quite short; about five minutes, twice a day. That is for the trick training.
Then, each lunchtime however, I take her to the local park and do some strict heel-work and loose-leash training with her, and that can last for up to about fifteen minutes. At the end of this, we just go over tricks learned too.
for me it depends on what we are training, as my dog has different attention spans for different things and in different environments. we quit while we're ahead and definitely at the first sign of deteriorating attention. For some things this may be a minute, for others it may be 10 minutes.