For example, I went from web-hosting software to fitness industry software. There is very little overlap in skills beyond 'writing software'. At hosting job, scale was the biggest issue (dealing with hundreds of millions of events per second) where now, legal/insurance type issues are the biggest hurdles. It requires a totally different way of thinking and knowledge set to be effective at a senior level. If you're just focused on 'writing software' then you're not senior material, you're just a programmer ... not an engineer.