The period between 2000 and 2003 is kind of hard to draw any conclusions from or the classify as "not having quality problems". That period started with quality

The period between 2000 and 2003 is kind of hard to draw any conclusions from or the classify as "not having quality problems". That period started with quality problems and saw Apple scrambling to make Mac OS X a reasonable OS to replace OS 9. For example, 10.1 re-introduced disc burning which was missing from 10.0. OS X 10.0 was also riddled with kernel panics and really sluggish. 10.1 continued to have pretty severe crashes and sluggishness, and I remember Jaguar being the first thing that approached actual usability. Panther arguably ended this transition period (where people were still unsure whether to "make the jump") and ushered in the more stable phase I'm referring to (2003 - 2011). And sure, if Apple only focused on a very sensible amount of changes, then of course a year would be enough. The problem is the contention of a 1 year release cycle and "150 new features!".