1. Rip up their policies and procedures and resolve every issue with ad hoc solutions
2. Stop having clearly defined roles and responsibilities and get people to work on whatever fire is currently burning brightest rather than what they are god at
3. Scrap budgets and most financials controls because it takes too much time and X is always more urgent

You get the gist. A lot of what companies do they do for a reason. It's a series of bitterly learned processes and systems that enable them to deliver quality consistently to their customers at an affordable cost.

Startups aren't like that. They are still figuring everything out. As a result they don't need most of the above until they have got it all to work.