Patch panel or filler

[wilberweb]

Hi, I am a novice body man. lack of finances mostly so I am doing my own body work with patch panels,welding the works. I don't have much experience in Body work.
my question is on a floor pan or any area that has miner rust, just a small area with a small amount of rust. Is it better to replace the area with a patch of steel, or just fill in the holes with body filler or weld up the small holes with weld filler? or a combination of both. here is a picture of what I am talking about
Thanks

-Larry