I only pin through a part if there is no other way to pin it down.

With T-pins you use the "T" to hold a part down and the pin part to hold it to the board.

If the part is too thin for the "T" to touch it, then insert the pin into the building board at an angle until the "T" holds the part down.

No sense poking holes in your structure if you don't have to.

Don