I appreciate the fact that you went this far! but context (of the app) does not mean you can go ahead and go all minimalistic on your users. Clear labeling when dealing with navigation of your app is required. Period. Say, you are new in the market and launching a new product. Do you want fast adoption, or wait for users to “learn” your design language. It is realistic to slowly take your product towards a more minimalistic approach when its the right time, but then again you would not be friendly to new users trying out your product. Imagine an app for doctors that deals with patient data from the Operating Room that nurses also have access to. Are we going to go all minimalistic on sensitive information because they need to “learn” the design language first?

Context is certainly important and the right icon is even more important, but are you going to gamble the efficiency of your app over a label? Does your grandpa care about your icon without a label? or the potential investor who only has 10 secs to skim at your home screen? Frequency of use, yea important, but that is assuming they are still using your app or users have “learned” your design language without the important labeling. With labels, frequency of use is irrelevant.