I noticed hardly anyone uses gameday prep up here, and everyone changes tactics enough that it would only make sense in the direst of circumstance -- and then the slim hope of getting a win might be outweighed by the potential loss of point difference. Last season I knew I was the favorite going in, that underdogs would try and take a flyer, and before the season completed my ongoing project of making my team almost perfectly balanced. So I was able to switch tactics with virtually no penalty, just to make GDP unviable and gimmick defenses.
Against Baker Street I didn't use GDP, but I figured I was an underdog and pulled out that crazy 1-3-1. It worked, but if I'd lost by 5, I'd have kicked myself for over-coaching.