Have a door that keeps hitting the rug or is dragging the floor? I can install a new threshold to make sure the door is clearing the floor/rug but is completely water tight! Most homes that I run into is when the doors were installed in the 80s with metal interlocking Chanels. These tend to get bent over time. At Mr. Door Guy we use Rubber weather door sweeps so you get a nice smooth close.
Do you see the light?
When you have a tight seal you shouldn't be able to see the light when the door is closed. Do you have a bunch of DIY pieces trying to fix the gaps?
When putting new weather stripping on an exterior door it should be clean with no gaps. Can be done in most common colors.