Dave.... Yes, one should ALWAYS follow through.

And you are correct that there are different views on the subject such as..... One should punch all the way through to the back of the target (in this case a bag) or one should hit the target with the idea of touching the spine, or one should aim to penetrate about 3 inches deep....

Either way you slice it, one has to punch through.

I use a 100 pound UFC bag... I hit it both as hard as I can with long and short punches, as well as lightly.... but always through..... By striking (not glancing if that's what you thought I meant)... not pushing.

The bag should *pop* not swing.

That happens from minimal contact time and kinetic energy... a push doesn't do that.

Maybe you just need a heavier bag as you say.