Well, Ok is kind of a relative term. What you described sounded pretty ideal. Our puppies were always left from 9 am to one pm, then I came at lunch, then they were alone again from 2 til 5. They did well with that arrangement.
But, I've known some people who needed to leave their pups for 8 hours every day. That makes potty training difficult, but it can be done.
For pups - usually their age in months is how many hours they can make it before running the risk of an accident - due to not wanting set backs in house training I would err of the side of that number to prevent accidents however you can leave them alone for longer if they have somewhere to go (piddle pad as you said).
As adults I have days when they are left all day and days when we are home all day - once you get through the puppy phase it gets easier.
Well, I've been too upset to write about it but Monday did not go well
When I left for the afternoon, she seemed happy though I just slipped away. But when I got home she ws whining, licking her blanket obsesively and wouldn't look me in the eye. She eventually made eye contact after about 8 minutes or so of licking and whining then stared at me and accepted some treats. She was intense and out of sorts for nearly an hr and has since shivered whenever I get ready to go out (in bathroom, or grbbing coat) even though I've taken her with me.
So I guess it was too long- back a few steps to condition her to being alone for more than 5 hrs even with an hr long visit at lunch. (I don't expect her to hold it, she has a piddle pad)