I have heard a story of a kitcar owner who thought he would run his engine in......he put his car on axle stands, started it up, put it in gear and let it run at low revs while he went and has his tea.
That engine didn't last long.
Fully agree with LittlePip's comments.
well i'm talking about new engines here i take it our mate with a kit car had his engine rebuilt in which case there are a hole load other things you have to do
but axel stands running in gear at tick over still sounds stupid to me