In all of the years I've smoked pipes I never had one that couldn't be smoked multiple times a day. The issue isn't briar, it's the smoker. Ever looked at cross sections of bowls that have seen decades of use? It's instructive. Barely any penetration of the briar by oils, tars, or other deposits from smoking. What you do see sometimes are char on the chamber walls and cracks near the base of the chamber, caused by excessive heat and moisture. That's the result of stupid smoking habits - smoking wet tobacco while puffing like a steam locomotive, and trying to burn every last little strand of weed at the bottom of the chamber. A briar pipe can take a lot of use, but a determined moron can destroy anything.