Yeah, I get the feeling that at this point I'm doing about as well with just looking up my grammatical questions and issues for Welsh, as you with a book + Duolingo for German. Quite honestly, I don't think I've come across anything that I didn't manage to figure out quite thoroughly, and just today I've defeated a construction where a subordinate sentence starting with "the reason why" for some reason continues with a definite article... Well, I guess you can't say I solved it thoroughly, but based on my research that's just how you form sentences like that.

Although I only manage to get through a sentence or two a day... Well, on the other hand, it can take me up to half an hour... I guess there's pros and cons to everything.

However... yeah, at least for Welsh, so far freeform browsing of the internet has performed much better than what I remember of textbooks for previous languages. I feel more motivated, I understand things better... And yeah, I may get frustrated, but I'm never bored, which has often happened with textbooks. But I may be at the right time (not the place, of course). I can imagine that only a couple years ago Internet resources might have been much more sparse... And of course, there's a certain allure to a well put-together textbook. Which extends to bragging material if you've got friends coming over. Proudly displaying Internet bookmarks doesn't really make a lot of sense.