Slide-In Spring Clips

I too have those horrible plastic butterfly clips on my window openings to hold the screens. Happily, I've just moved into this home and the screens are in bad shape so I will have to replace them as well, meaning it's easier to use corner springs in my case (plastic corners). The screens fit closer on the sides and 2 butterfly clips are installed at the top and bottom of the screen opening so you can move the screen up and down slightly to remove it. My question is what is the most economical number of spring clips that would work - one on top, two on the bottom or do I have to use four? or perhaps I could use one corner spring on the upper left and another on the lower right to keep the screen in place.

Also, the channel that the butterfly clips sit on is not flat, it has two horizontal humps with a 1/8" space in between, so I intend to order the 1/8" corner springs as I assume they will fit better. Could you tell me how high the spring is? the descriptions show the length but not how high the hump of the spring is. Thank you for your time and expertise, Virginia.

Paul (and Donna too), this information helps me tremendously. You have great expertise. I am so happy I will not have to buy expensive butterfly clips that will disintegrate in a year but can retrofit my screens with the 70-193 stainless corner springs. Since this problem is in a sun room with screens on three sides it is a big relief for me. Thank you again so much.
Virginia