I often use it like hippy does on the basis that:
a) The person I'm speaking to may say they understand it but actually doesn't, and the negative effects of them not understanding something could be a pain in the arse for lots of people further down the line
b) and/or I've been shit explaining something and they're being polite and not telling me that
However, some people definitely use it in a hugely condescending way, similar to the way people say "Only an idiot wouldn't think that..." when trying to stop people questioning why someone is talking shite.
It depends.
I often use it like hippy does on the basis that:
a) The person I'm speaking to may say they understand it but actually doesn't, and the negative effects of them not understanding something could be a pain in the arse for lots of people further down the line
b) and/or I've been shit explaining something and they're being polite and not telling me that
However, some people definitely use it in a hugely condescending way, similar to the way people say "Only an idiot wouldn't think that..." when trying to stop people questioning why someone is talking shite.