As someone who has never smoked, even after six months with the pipe my mouth still gets sore if I have one bowl a day.
I prefer not to have more than two bowls a week.
Now, that may have as much to do with my noob puffing cadence as anything, but as for recorded history of people who had "too much", you can look at Sigmund Freud, who was well known for smoking constantly and developed oral cancer.
Of course, it's a game of chances, but I like my chances to be somewhere around 0 wherever I can manage.
I prefer not to have more than two bowls a week.
Now, that may have as much to do with my noob puffing cadence as anything, but as for recorded history of people who had "too much", you can look at Sigmund Freud, who was well known for smoking constantly and developed oral cancer.
Of course, it's a game of chances, but I like my chances to be somewhere around 0 wherever I can manage.