I almost never go to a 7/11 in the US but every time I go to Japan I visit a 7/11 at least once a day. No matter where you are in Japan there's likely a 7/11 within walking distance and besides the usual assortment of drinks and snacks you can get quick full meals there of high quality.
Conbini meals only register as "high quality" to you because your comparison point (e.g, American 7-11) is an abysmal excuse for food. The food is, in reality, not that special.