I can't speak to the specific Showdowns but the mode itself just takes some getting used to honestly... just have to take a look at the mission and strategize accordingly. Granted my way of doing programs is to save Showdown for last (or next to last if you count playing MTO and other modes for Gameplay XP) after I complete the Conquest map, Moments and Missions for any given program... and so far so good... I still have yet to get to 100% completion on a program (I think outside of the Los Angeles Angeles Connect Uniform Program) but I have been able to get Bosses as well as cards that I missed out on from previous programs and other cards that will help me get the jump on some of the other programs where you couldn't get the actual cards for the program (Always Intense and Big Dogs for example) until later in the reward tree.
Maybe next year I'll really get my grind going but this year I'm actually having fun with the game after missing out on the last 2.5 close to 3 years.