In terms of RM charts, this is a topic that has come up before. There are several charts, some based on controlled scientific studies, others on informal observation of a number of lifters, and most charts are in close agreement. If you read between the lines, some studies use untrained individuals, others use experienced lifters, so you need to be aware of that.
Most represent typical athletes with at least some weight room experience and are based on the ‘mode’ or ‘mean’ number that athletes performed to failure. Not everyone hits the exact number on the chart for a specific RM percentage. Some get less, some get more. Most probably fall very close to the number on the chart.
I am 49 and I know I can normally get right on the number, and can often exceed the number by one rep, although I don’t test this very often. I use a slow eccentric in training and may have more strength endurance than a lifter that always uses a fast eccentric.
I work with a 21 year old powerlifter that benches 805 with a shirt, and high 500’s raw, and a 24 year old powerlifter that benches high 400’s shirted and 375 raw and both can meet or exceed the charts, again I think because of using very slow eccentrics in training.
Charlie has alluded to the fact that Ben could exceed the charts probably because Ben possessed a very high degree of strength endurance.
The charts aren’t perfect, and everyone should have a good feel for how may reps they usually do at a given weight, but the charts are a good place to start and are fairly accurate (within 1 rep) for most lifters that do not possess either very high or very low strength endurance.