grappling: trapping or tie-ups?

When you teach the grappling aspects of JKD (original material is what I'm interested in for this particular question) do you work from trapping, a tie-up or both? Also, if you teach the tie-up, which tie-up(s) and how much striking is involved while in it/them?

Personally I prefer using the tie-up for grappling techniques just because it's easier, but I do see the potential for efficiency of going directly to grappling tactics from trapping when possible and train that as well.

Please, any opinions are welcomed.