Re: Is two Days a week enough?
I started with one day per week, just to accompany my big son. After two weeks I found out that that was by far not enough, and we went twice a week. Then I passed my 5th kyu, became ambitious and said that until 4th kyu I'd train better 3 times per week.
Then all my kids enrolled in aikido and I started to train four time a week. Now two of the kids left aikido again, but I still train four times a week.
For physical fitness I don't see it makes much difference, but then I am someone without car or television, going by bike everywhere and moving around a lot even without aikido.
For learning I think it is the necessary minimum because I'm not one of the naturally aiki-gifted whose body learns easily. I have slow reactions, bad sense for distance and lots of typical female submissive habits I'm not aware of but just don't get rid off (like shrinking back and bend my arms when someone attacks). So even with four times a week I advance slowly, but I advance, and that's enough.
There are several people in my dojo who come twice a week, and they advance more or less at my pace. There was a guy who came once a week, and he made zero progress.
But on the other hand - there is also work, family, friends, other hobbies - you just have to look where is the best balance for you.