It is often said that writers should read more to improve their writing. If I only have limited time to read, should I stick to reading only the genre that I am focused on writing or will devoting a percentage of time to other genres be just as beneficial?
I think you should definitely read outside of the genre you intend to write in.
Reading only in the genre you love will lead to a greater tendency for your work to be derivative of what already exists in the genre, without bringing a new voice.
Reading in other genres will bring new influences to your genre, which will allow you to elevate the genre and stand out in the marketplace.
I think you should even practice writing in other genres. Just like athletes cross-train, this will make you more robust, adaptable, and increase the value of your voice in your primary genre.