there are a few variables that come into play here.
dirty ball and P/F (it doesn't take long for the balls used in new machines to lose their shine, no shine means ball moves slower)
the pitch that the machine has been setup at.
binding flipper bushes (I have come across a lot of new machines with little or no gap set between the bush and flipper)

the flipper components on new machines just don't last as long as earlier machines, I have seen a lot of ex sited machines that are only 1 or 2 years old that need flipper kits.