1. Number of costly discoveries when actually installing new stuff after carefully planning everything before purchase
(rule of thumb: zero is unobtainable).
2. Number of times the bolt holes for the new stuff lines up with the old holes.
3. Number of times the good old hardware
can be found when it comes time to reinstall it.
4. Number of times the wierd sized old bolts and nuts can be found to reinstall the good old hardware
Anybody who claims perfect rates is not telling the whole truth. (Hope the admirals aren't reading this disclosure.)