first off im no expert like glen but im in the process off doing my studio so i can only tell you what ive learned so far.
in answer to your question there is no answer. not very useful i know but thats it. without doing some sort of sound test there is no way of really knowing what and how much to put where.
when it comes to bass traps, you can never have enough. where 2 surfaces join is where bass will build up so thats where you will need a trap. just remember there are going to be at least 12 corners (2 surfaces meet) and 8 tri corners (3 surfaces meet) in every room. (based on 4 flat walls only)
early reflection points need to be taken into consideration too. these are the point between you and your monitors, left and right walls, floor and ceiling.
these are just the basics.you then have to consider front and rear walls etc....etc...... you could go on forever.
what size/material is that foam? doesnt look very thick to me.
