This is correct only IF you are running a gear ratio that is too high. On a Dana 30, a 5.13 will leave you with a pinion that is really small and then, there is merit to what you are saying. On a Dana 44, this would be true with a 5.38. If you go a size down, your r&p will still be stronger and I would highly recommend that you get a chromo shaft upgrade.
The most common side for a break to occur is the DRIVER side. This is because it has LESS shaft to help absorb shock. This occurs so often that I often recommend that if you can only carry one shaft as a spare, that is the one you should carry. The passenger side can break too but, it's not as "common". Of course, this is to say nothing about breaks caused by u-joint failures. If you run chromoly shafts with full circle clips, you can prevent that from occurring.