There are many shapes and sizes and all are designed to "sheer" the ink from the mesh and transfer the ink to the garment. I’m not going to get too deep here as there is so much to cover and the manufacturers will send me tons of letters defending each size, shape durometer and such.
I use 70 durometer square edge squeegees with 2" or less of blade extending from the housing. Set at angles between 75 degrees and 65 degrees this does the job perfectly for textile printing. Proper screen tension (tight) and proper squeegee pressure does the job of "sheering" the ink. Do what you will, but this is how I would set up your press if I were at your place.
Take a look at high-end squeegees such as the "constant force squeegee". Its blade is so small and it’s angled at 65 degrees (close to it). Clamped into the printer at 90 degrees and the rubber is auto set to the proper print angle. Yes, I know it takes a very level platen to take advantage of this great idea (not all can), but hey, right is right and if we can’t create a perfect environment now at least we know what we are shooting for. Strive for it in every way you can but take from this information as it is intended. That crazy shaped housing is focusing the pressure down the tip of the blade where it belongs.
Frankly, the next time you see your blades doing the "limbo" on press back off the pressure as you are not helping yourself.
