I honestly try not to spend too much time thinking (think <1 hour), but still put a little effort to make a deck. Given that Platinum's advantages help compensate for my deck-building skills (or lack thereof), my last 3 or 4 seem to have done well. I would usually get something like 15-2 or 25-4 before I change decks. It's good enough to crack the top 100 or hover around there and I'm satisfied with logging in to Elements the next day and finding a free 100

. And again, it's based on the oracle, because even if I have a good deck posted, I may still submit something new because I want to use the new card given to me by the oracle.
So all I'm trying to say is, you can spend like 30 minutes to make a good, somewhat original deck with some quick testing. It's like the oracle is giving me extra

each day.
On a side note, I got Immolation as my oracle card today, but didn't make a deck because I was tired of seeing Immo rush decks all over the place.