R D S wrote:
Positively I suggested that he had learned some pitfalls and gotchas so
that if he was to fit a sink again it would be easier and he'd do a
better job.

His retort was that he'd learned that if he needed to fit a sink again
and wanted a better job doing he'd get someone in. And i'm pretty sure
he was serious!

It's useful to know when to play to your strengths and when to delegate.
Subcontracting a job costs money, but if you contract it to someone who can
do it quicker and better than you then you get a better result at the end of
the day, and you can use the time saved on something more profitable. If
you can't see you're going to be installing many sinks in future, why would
you invest in learning that skill?

Theo