Just look at the Vacuum gauge on idle or even slightly higher power settings!!
I thought the regs for IFR flight say that the instruments (AI) must erect within 5 mins at idle (ie. while taxying).
Why do you think God made aeroplanes with 2 engines, 2 altimeters,2 Vacuum systems, 2 Generators, 2 VORs, 2 Radios and even 2 pilots?
To double the chance of an accident
Seriously though, many "new" A/C like newish 172's have two vac pumps, but i agree its lack of PP training that kills people. I think anyone in their right mind who flies singles in IMC should practive PP stuff, if not then its their arse on the line.
I was doing PP stuff in a Seminole, and as we started transitioning the clouds while being vectored to the ILS my instructor "failed" an engine. So now, in IMC, partial panel, trying to identify, verify and "feather" the bad engine, with only PP instruments was "fun". Still, I learned a lot, it proves it can be done.
One other point, I saw a vac pump failure on a seneca, which casued the whole system to fail for some reason.....Don't know why, but its worth remembering that it can happen.
Cheers
EA
Cyer