No need... they were all over the place where we went!
AT: i didnt take them all! but you do need to find a nice spot indeed... environment is everything! once we were in too 'clean' a forest and not much chaga was there. Another time, it was the opposite and the forest was modly everywhere and there was Chaga, but the quality was low because it wasnt growing on very healthy trees!
But dont let that discourage you... In almost all forest where there is birch there will be chaga. To find big chagas, look for big birch (older forests) In the north of laval thats all there is! ;)