I probably think differently to most and you could argue it costs me from being a genuine contender but I much rather select the guys I want to pick not pick with 3 rounds of the season in mind, one bad round really isnt the end of the world.
Best 18 certainly helps and, like any other round, the key is to avoid donuts. I also tend to focus on the total score for all three rounds rather than the highs and lows. At the end of the day, it's a sum of 57 scores (54 + 3Cs).
In the past, the assumption with your "keepers" is you've got them for 2 out of 3 rounds but I think the extra trades will provide more opportunities / temptation for premo sideways moves this year. Whether that's a help or a hindrance remains to be seen.
Coming back to the original comment, the boosters may also prove useful in the first two rounds - making adjustments to grab the right rookies / tinker with structure but it's a long way to the finish from round 2 so the risk is greater.