How important is line progression?

Lindsay

I see a lot of you ladies posting photos of your line progression saying how good it is since it means your levels are getting higher. Today is the day AF is due and I got my BFP on the 19th. These past 3 tests still show a line but it doesn’t appear to be getting any darker. Is that good or bad? I took a cheap test today too and the line showed on that one.

What do you guys think?