Back when I used the Kindle for Windows version I did the manual install because I had the same issue. I would periodically check for updates. But since I no longer mess with deDRMing, I rarely even open the Kindle app on my MBP. It is so much easier just to open the books in my Kindle for iPad app. I'm not sure if the issue with updates not being pushed out in a timely fashion is the fault of Amazon or the Apple App Store or perhaps both. It does make me wonder what else I have on my MBP that might have updates available that I am unaware of. I suspect the issue is with Amazon though. When I had a Fire HD 6, I would usually get updates fairly quickly, but some people were having to wait 6 months or more before their updates got pushed to them. So Amazon definitely has a history of slow updates for some people.