If most of science is normal science where you have a tough idea what you’re doing yes. You may not know the solution to your problem but you know the problem you’re trying to solve and mostly your trying to solve it with the same tools the rest of your discipline is using. Even when that’s not true you’re trying to finish a PhD faster than other PhD students or to publish more or better work so you can get a better postdoc. There’s a lot of competition.