I have some questions.
1: Would it be such a horrible thing to do RtK and say Genki 1 at the same time. From what I understand it is recommended to do RtK first but I was figuring it would be nice to get a bit into the language proper at the same time and G1 doesn't seem to go too deep into things. Either way I'd assume Remembering the Kana would be a good idea before heading into the textbook stage.
2: This is more far, OK, really insanely far down the road. If one were to reach a level N1 proficiency both in comprehension and production [as I understand it, the tests don't really cover writing and speaking] and one doesn't live in Japan, how much time would someone have to put in a week with native materials and the like before regressing in skill. Even my own father started to lose a bit of his French after 30+ years of living and working in English and that is after spending his first 20 years in a solidly unilingual French environment. It would seem to require quite a bit more time than a Euro language to keep up as well as to learn. If anyone has any experience with learning and maintaining other non Japanese languages, I wouldn't mind hearing them.
1: Would it be such a horrible thing to do RtK and say Genki 1 at the same time. From what I understand it is recommended to do RtK first but I was figuring it would be nice to get a bit into the language proper at the same time and G1 doesn't seem to go too deep into things. Either way I'd assume Remembering the Kana would be a good idea before heading into the textbook stage.
2: This is more far, OK, really insanely far down the road. If one were to reach a level N1 proficiency both in comprehension and production [as I understand it, the tests don't really cover writing and speaking] and one doesn't live in Japan, how much time would someone have to put in a week with native materials and the like before regressing in skill. Even my own father started to lose a bit of his French after 30+ years of living and working in English and that is after spending his first 20 years in a solidly unilingual French environment. It would seem to require quite a bit more time than a Euro language to keep up as well as to learn. If anyone has any experience with learning and maintaining other non Japanese languages, I wouldn't mind hearing them.

My point was sort of that even studying French seriously, there's still news I want to catch up with, people I want to chat to, hobbies I want to pursue, and many of those naturally involve using Japanese... enough to keep improving my Japanese. But yeah, I get your point about only so many hours in a day. Trying to maintain more than a couple of languages, in particular, seems like it would involve more conscious planning :/