It doesn't have to be with a complicated tool, either. I knew that lesson from years of shovelling levees in rice fields, but I relearned it one summer working construction. I was told to remove the bottom three courses of a very hard concrete brick from the back of a building on which we were building an extension. The first day, it took several hours wailing with all my might with the sledgehammer just to make a hole (remember, young, 200# 6' and spent my previous summers shovelling, throwing fertilizer bags by the hundreds for the crop duster service). I got a few more out that day. The next, within 30 minutes I was removing each brick with three hits, and not using all my might but aiming better, and finished before quitting time.
Pete Keillor