If you are an entrepreneur, you follow you intuition and decide how much money are you willing to spend to see if your idea works. You are quantifying the amount that you are willing to lose on a venture. If everyone followed only numbers, there would be no innovation, no R&D, no risk takers. The majority of people follow numbers because most people are risk averse. Entrepreneurs are in the minority. Angel investors may support entrepreneurs.
If your business is static, not growing very much and well established, you will be watching the numbers very closely. If you are a start up, you have no history of numbers to follow.
In summary, following your intuition is dependent on what part of the life cycle is your business. Is your business in the start up phase, are you an old established business, are you a risk averse owner or are you a risk taker?