The other difficultly is that often your working hours are the very least your leave them.
So if i work 8-4 then thats 8 hours. However if my commute is only half an hour thats 9 hours. If you then add in any time eg to pick the kids up it easily creeps up.
So say your dog is left for 9 hours, then you've come back for maybe 2 hours, then gone food shopping for another 2 hours.
Its easy to forget that essentially the dog is in its bed or expected to have limited interaction say 10pm-6am then if its alone while your at work 8 til 4 plus commute then out of its 24 hours your looking at least 17 of them being spent alone.
That gives your dog 7 hours with you, in that 7 hours what will you be doing? I know that i spend 1 hour getting ready for work, at leat 1. hour to cook dinner and eat dinner, about an 1 hour sorting house out eg washing up, laundry, hoovering. So now the dog is down to just 4 hours spent with any attention, ignoring any time for things like wanting to sit watching tv, or stopping into tesco on the way home, picking kids up or doing anything extra like dinner out or cinema.
Its amazing sometimes how little time we expect our dogs to have. I think we like to think our dogs are frolicking round the house, but my dog certainly is sat waiting for someone to return. You'd never expect to crate a dog for that period but because you can't see them you dont realise how boring it is for them