I use one of these in the shower(1-2 times a week regularly, more as needed), usually after using a psoriasis specific shampoo used to loosen up buildup of dead skin (usually t/Sal, but whichever one works for you). It helps exfoliate once the dead skin has been loosend by the shampoo and stops most of the flakes at the source.

(Edit) I find this comb is also a bit more gentle because it's not one single point of contact with the scalp, it's slightly softer plastic so it will conform to the shape of your head as you use it. That way you won't scrape or scratch your scalp during use.