Actually you don’t need worry whether your post related topics with current timeline or not. But you should read local timeline because if someone mention to your post, they will not to be use @username mention tag and then you can’t notice it if you don’t read local timeline. Almost users expect that you read local timeline.
@dangero You should use @ mention if you are talking with only specified users. but usually you must not use it because it will not appare to local timeline if you use @ menthion,