How does only writing the CARS section work logistically?

I’m writing next week and for various reasons, I’ve decided to only write the CARS section this year. For anyone who has done this, how did this work … can you skip the first section and then write CARS right away, then skip the last 2 sections? Can I leave after writing CARS?

Or if anyone can direct me to a recent thread about this that would be appreciated! Thanks.