The best form of evaluation is to see progress in every workout. Unfortunately, for every 10 workouts, there will be four in which you’ll suck hard, two considered “ok” by overall standards, three amazing one’s and one that you’ll probably miss.
Even though you might think you are not progressing, there is a few things you could look at, beside a weight load increase, to see if you are doing better or not. Keeping a training log is without a doubt the best way to observe progress. Whatever it might be. Here’s some other elements that might indicate you are on the right track toward your goals.
Have you done more reps than the previous workouts with the same load and rest time? Were the sets easier or more controlled? Instead of giving a specific repetition goal (like 6 reps), I give a rep range, let’s say between 8-10 reps. First week, finding the correct weight is the challenge. Second week, you aim at maxing all the sets at 10 or maybe on the last set increase the weight to finish off at 8 reps. On the third week, you take the last set weight, which you maxed out at 8 reps, and do all your sets of 8 or 10 reps, only to try and beat that on the last week.
If it’s the same matching intensity than the previous workout, are you taking less time to recover? When I work with my elite athletes, I use the heart rate monitor to see progress. A few seconds less to recuperate between sets of their conditioning workouts is progress in my book.