udpp is just a base to hold your loose dry shadows, since powder will eventually go away because there is nothing to hold on to. you can use a shadestick in lieu of udpp, the magic of udpp is that it seems to make shadow last FOREVER...
i mean, put your makeup on friday, fly to vegas, get loopy, married, wake up with a hangover, have marriage annulled, get drunk all over, gamble away the house, wake up sunday, fly back, look in the mirror, and wonder when you reput your makeup back on... but you didnt. it was jut Frday's UDPP.