Is one year between WWDC´s too short for IOS major releases?

Hi folks,
I am wondering if one year between each WWDC is too short time for IOS development as I see so many bugs in the beta versions - and every year it seems to be harder and harder.
Many basic functions are not really working from one IOS Master version to the next. Why? Are they always changing every core module every year?
For example there are bugs with on screen keyboards on IOS 12 - why?
I am really not sure that this is the best way - wouldn´t it be better if it will be a Tick - Tock development where every two years the basisc are optimized and in the next year only optimisation and some small improvement are done? Similar to Intel´s strategy.
Our developers have more and more work to do with upcoming IOS versions - more bug fixing needed, higher costs, more work.
Every year more devices with different resolutions remembers me more and more that Apple went in the android trap.
So I think it would be great if there will be a re-thinking about that, otherwise we will stuck in a Android / Microsoft mess as the collegues in the other department.
Many greetings
Hartmut