The expectations of SpaceX have varied greatly over time. Experience has taught them many lessons.
This initial reuse had many components replaced. The goal is to understand why those components needed to be replaced, build them more robustly so that they do not need replacement.
As Mark Adler's answer notes, the first reused booster will not be reflown a third time, but future Mod 5 boosters (the context of Mark's quotation) will be more resuable as that model is meant to be the culmination of the lessons learned from reflight testing.
In addition to simple resuse mission (SES-10), SpaceX has declared in the past that rapidity is also important. Thus things like how to reset the legs will need modifications. (This is one of the assumed modifications in Mod 5). If it takes 3 days to unload a stage, remove the legs, swing to horizontal, drive it back to the pad, you cannot relaunch in 24 hours as is the goal.
Musk suggested that the Mod 5 design will allow 10 reflights with minor touch work (refurb). Then with more major refurbishment should be good for 100 flights or more. The idea being, the core stage, and most of the major components should be good. Some parts are good for 10 flights and then need to be replaced. Each landing attempt gives them more data on how parts weather the reentry and allow them to test ideas in how to make the weakest link parts, last longer.