Startups tend to be the worst of both worlds. All the process of big companies and al the risk and turmoil of small ones. Not worth it except to be a founder or executive. Anything else, you should instead get a big company job, get a promotion or two, and use the name and momentum to get something with real upside.
There are startups and there are "startups". Lots of medium-sized (>150 people) companies call themselves startups but are filled with big company people and their big company practices, held up in many cases by a steady stream of VC. Real startups don't use bigco process.
What do you consider small? I feel like it’s just the luck of the draw if a company has decent management at all levels or not. Small startups ( I would say under 50 people ) rarely have a lot of process and hierarchy