This is something very important if you want a good career and the flight schools are not honest about it. Do what you can to not have any failures. They will weaken your chances at the majors and in some cases be a complete dealbreaker. Being ready and well prepared goes without saying. Everyone knows who the easy examiners are. People get grief for going to the easy ones, but the airlines won't excuse your failures because you had a tough examiner. Get an opinion of a CFI other than yours to see if something is missing before you take the checkride. Don't let a manipulative flight school push you in to bad ideas during your training. .