Mmmm. Another popular saying used by those who have lost there own faith and thus part of themselves.
To personalize shows me only your lack of self esteem and confidence.
*shrug* I have enough self-esteem and confidence to value intact shoulders more than some stranger on the internet's opinion of my training.
And that's really my point in this whole sub-thread, too. They are MY shoulders. I simply DO NOT CARE what you or anyone else thinks they "should" be able to tolerate. I'm the one who is attached to them and will have to live with the consequences of an error, whether my own or nage's. So I will tap when I think it's appropriate, and I will avoid practice partners who don't respect that.
Again, if you think I'm tapping too soon, it's your job to convince me that you can be trusted with MY shoulders. How to convince me? Well, you could start by letting go when I tell you to. If you can't be trusted to do that, you certainly can't be trusted to help me stretch my limits.