It's not really about how you start, or how you end. It's about your structure, and game plan. This should start with your ranges. learn them, memorize them, and stick to them. Yea you need to adjust them from time to time, but that comes with experience. Cause without them you are going in blind. I have so many different ranges I have a hard time keeping them straight. That's why you need to also study off the table to see where you made mistakes. This will help you make those in game adjustments when you need too.
Now as for a field that large, think of it like this. A profitable tournament player cashes about 30% of the time. That's of typical field of about 50-200 people. Now for the
wsop ME event. Where most of your players are very familiar with GTO, ICM ect. your looking at a field of about 7000, and your cash rate for a typical player (even pros) is at about 20%. When you get up into the 10k+ range. Even if it is a bunch of rec players. Your cash rate is still only gonna be around 10-20% and that's if you really know what your doing, and make no mistakes at all.