Oops! Shouldn't have assumed the thread was just about work.
It's interesting when you think about how other experienced mothers in the family respond to a new mum in the family - how many of us have not been on the receiving end of floods of unrequested 'advice'? It's not that I object to advice per se, but I do object to people offering their wisdom when you've not asked for it. It gives the impression that they think you're an utter brainless twit who has no idea what you're doing, and the natural corollary of this is that they believe they are the fountain of all wisdom on the issue they're pontificating about.
It does seem that when a MIL (I'll use that term to encompass all experienced mums in the family) continually tells her DIL what she's doing wrong as a mother and what she ought to do instead, her first reason for doing so is not actually to benefit the DIL but to boost her own self-esteem about what a fantastic mother she is - i.e. she's saying 'my way is the only way to bring up a child'.
This is certainly my experience of mums in my extended family.