I agree it is a valuable lesson Martin needs to learn
But in the case of Elaine, I think it was just a miss by the writers. The character didn't work and the shtick grew tiresome fast.
I think that's why they went in a different direction in Series 2.
But perhaps there Is a behind-the-scenes story to the change in receptionists??
Lucy Punch - Elaine - was offered and accepted a movie role in the US.