I would say that culture matters a lot more in the hiring/interview process when you expect each individual you're hiring to be a multiplicative force. For smaller startups that are growing, this tends to be true. For larger companies, they tend to grow more linearly, so an individual that only contributes raw units of work is usually sufficient. So I don't think it's purely the percentage of the company that each hire represents, but more so what you expect out of each individual.