Sounds just like cluster feeding. Perfectly normal tho for some reason it is not really covered in books. I only found out from talking to other mums and coming on here. My LO has cluster fed for up to six hours during growth spurts, 30-45 min feed, doze on breast then start again. It's how they grow!
Some babies doing this all the time and with other signs of distress or struggle inc poor weight gain may be signalling some difficulty.
But you said feeding 'on and off' - not feeding literally without a break, anyway, and that sort of 'cluster feeding' is very typical.
It's simply incorrect that feeding for an hour at a time is something 'wrong'.
There are some people who declare themselves as bf experts/advisers/counsellors and they are nothing of the sort. Or they may have a low level qualification and over-step their boundaries. Or maybe in this particular case - ie not yours - there is something else going on and other signs, and the bf person is right to be concerned. But not if the only thing that's happening is long feeds.
This is normal behaviour in young babies - sometimes they are having a growth spurt, sometimes they are just doing it 'cos they need and love the comfort, closeness and reassurance. Sometimes it's prob both
I would distrust any bf advisor who assumed a problem with it