Just a few things I've noticed. I've got 12 worlds, so trust me when I say I do each quest 12 times.
Random isn't really random: When I select the optional building type on either the Practice or Tourney, 80% of the time I get the same building I just traded for on the previous world. On top of that, it seems that 90% of the time it's one of the towers or a tower upgrade. Or I get Renovation buckets on my Iron Age world (happened 3x so far), big help there.
Without Diamond use, the average player has no chance to get into the top tier. For that matter, with the new way the Tournament is played, there's no way to even win against the hardest opponent. All the Youtube guides advise buying just one color card so they can outplay the other two. However, if everyone is buying Green, then when that player's team is your opponent, you can't even rearrange your team to a draw. Their card numbers are just too high. The Hardest team should be within 3-5 points of your best team to possibly allow rearrangement for at least a draw. Mid-level opponent maybe 5-10 points below, and easy 10-20 points below. As it is, I was only able to compete in the highest tier a few times in the early days of the game, past day 5 I couldn't even touch it, and that's on 12 worlds. So no possible chance to earn enough points to get into the higher leagues.