My mob (which I thought was The Revs old mob?) use the same philosophy as you state. 25% or max motoring.
We only have manual start (tight pr1cks), and I have only had one occaision where the fuel was thrown in at mm (23%) Lit off a little hotter than normal, but seemed to run OK. I imagine places like JNB in summer et al you may have a struggle to reach 25%.
$.02