You’ll get better results working your ass off on a bad program than you will loafing through a good program.
You can build big muscles with a bad program if you work hard enough. It will hurt, and you might injure yourself, but it can be done. You can also have the best program in the world, but if you do not challenge yourself, then you will never get anything worthwhile out of it.
The trick is to put the effort into a good program. You will make better gains than you would with a bad program, and you will be much less likely to hurt yourself.
I can say from experience that this is true, and that it extends well beyond weight lifting. My first few years of running for RIT, I was putting in 85 to 95 miles a week for most of three seasons, and 60 to 70 miles a week for the rest of the year. High mileage is nice, but there has to be more regular rest and recovery. Our workouts would be great, but our race performance on the weekend would suffer because we were always tired and beat up. We had one workout that was 5 hill repeats that were three quarters of a mile long with a half mile recovery jog down the back side. The problem came from the fact that the park we were running in was seven miles away, which meant we were doing a 19 or 20 mile speed workout.
That being said, some of my best race times came from those first few years before I hurt myself. It is only the last year or two that I have been managing to get myself back into that kind of shape. At some point I will return to the high mileage, but it will be a seasonal thing and not an year long training method. My best marathon to date, which was almost a half hour better than I ran when doing the high mileage, came off of around 40 to 50 miles per week.