Work like this is always done in parallel. There are multiple stages in projects like these. When implementation and testing is finishing on one project, if only then work would start on the next one it would be a ridiculous waste of time and available resources.

And well, if the next thing wouldn't always be better than the previous, there would be no point doing the next thing. Consumers need to jump in at the moment they think something is good enough for them.

"Everything you buy now will suck in 5 years", a cynical person might say.