I have always taken this for granted, since it is the way I was taught umpteen years ago, but I have been amazed at the number of people who don't know about it.
Whenever chopping moulding that has a flat top, turn it upside down. This has become even more of an issue since the "backbevel" frames have become popular - those ones that are flat and wide, but have a reverse bevel on the outide beck edge so that it looks like the frame is really shallow and standing out from the wall.
The only possible disadvantage is that you might harm the finish if you aren't careful - so don't do it on an extremely delicate finish.
Whenever chopping moulding that has a flat top, turn it upside down. This has become even more of an issue since the "backbevel" frames have become popular - those ones that are flat and wide, but have a reverse bevel on the outide beck edge so that it looks like the frame is really shallow and standing out from the wall.
The only possible disadvantage is that you might harm the finish if you aren't careful - so don't do it on an extremely delicate finish.