What chips are we comparing, chips in the same product range, or just in general?
Apple is perhaps the ARM architectural licensee that has the shortest cadence, although it has had one major architectural transition with more iterative changes since.
There are more companies designing ARM cores than x86, although their individual rates of product introduction are slower than the press-release collective ARM drumbeat.
Are there other vendors that are able to beat Intel's cadence--at least prior to its apparent tick-tock stumble in the latest generation? Intel actually has tweaked its cores at process transitions, and some of those transitions could have been labelled a core revision or a new core by other vendors.
Process-wise, 14nm FinFET has been in Intel products for quite a while.
There has been a gap in product requirements, where server-bound x86 chips can take a year or more than client offerings. That can be one reason for putting Zen's server variant after the client one, on top of AMD's products being part of the yield-learning process for GF.
AMD being beaten in iteration rate is because it is a struggling giant, if it can rate in that category.
For what it's worth, Intel also has a history of putting a lot more up-front effort into its cores, including the physical design and system integration, whereas ARM has historically left more on the table in order to make a more broadly applicable core, with incremental revisions that gradually work up better sustained performance or power-efficiency. The A72 might be an example of ARM making a more concerted effort to revise and target physical implementation better.
