I tend to agree with FlightDetent, and normally try to keep it very simple. I have flown with many captains, very good in this, and they made their mental math (A320) in order to get a very precise profile.
I see I can lose a bit of SA if I make it too complicated. So I simply make 3xheight, then depending on the speed I decide if I can accept the distance I get or If I should make more margins. The only time I have a fixed distance in my mind is when ATC keeps me high and stuck at an altitude different than the platform and close to the threshold. In that case when 3xht plus 3 matches my distance I start configuring.