Yes, although training camp has its value, sometimes it can be hard to see for players that have to live football 24 hours a day. First off, it can be tough for guys to measure their progress. In training camp, teams can usually only practice against their own guys, so not only do you have teammates beating up on one another, but you also get a number of questions that arise each time the starting units go up against each other. Until you get outside the team and play other opponents, you really can't gauge the answer to that question. Practices in the morning and afternoon tend to wear players down, and there's not a whole lot of time to rest and recuperate.
Little injuries crop up and get worse because there's no time to heal.
Still, for the veterans, these games can seem like waste of time, because many star players see the field only for a couple series before putting on the baseball cap and watching the backups duke it out for a roster spot. Everyone hides when the Turk makes his rounds, but if he comes after you, you can't escape him. The presence of the Turk gives some players the edge they need to make the squad, but it wilts others under the pressure, which is just another painful result of training camp. All in all, if they could have a fast-forward button and speed up July and August, most NFL players would do so. Some rookies and vets despise camp so much that they stage a contract holdout and conveniently sign on the dotted line the day camp is over.