Agreed. This [0] and the subsequent lessons go onto explain that if clauses change depending on whether something is a fact, whether it is an invitation, whether it is volitional, etc.

I've been studying Japanese for years and I am at a basic intermediate level. I still find grammar hard to read, and even harder to produce naturally. I may just be particularly thick but I think saying "you can master Japanese grammar in a matter of weeks" is pretty misleading.

[0] http://www.learn-japanese-adventure.com/japanese-conditional...