Plus it also lets the dealer know what you had been fiddling with !
I use paint spots as an easy way to let myself know that I have torqued something down as my memory is not perfect.
Cheers
Den
If your memory is not perfect, are you positive you paint every single bolt after torqueing it down?
My method is different: if I put a bolt or nut in, I always torque it down correctly -in case of a cover, I torque them down alternatively, but all of them at the same time. That way I always know that every bolt that is in, it has been torqued.
Only use torque wrench on head bolts/nuts and filter bolt. The rest are torqued by "feel".