Dennis, when smoking Ribs using wood chips, I add chips every 20-25 minutes ( about 5 times over 2 hrs ) and then none after that and the smoke taste is just right for me and some people, and a wee bit more smokey than prefered for others. This is usually JD chips, but sometimes 2/3 Hickory and 1/3 apple or cherry chips.
I think more than that over 4 hrs would be way too much. Just my opinion here.
As for pellets, I am still learning, but any smoke after 3 hrs here would do nothing for me since I foil my ribs around the 3 hr mark give or take a bit depending how much bone is showing.