If you mean startup in the sense of VC-backed with the goal of maximum growth and market penetration: Probably yes. If you rather want to do your own thing, I

If you mean startup in the sense of VC-backed with the goal of maximum growth and market penetration: Probably yes. If you rather want to do your own thing, I always liked the rule of thumb from the book "Start Small Stay Small". Put 100 hours into the product and 100 hours into marketing. You can do this in a month or two and then you'll see if it works or not – and more importantly: You will see if you like working on this thing or not.