It would be cool if after doing a verb conjugation quiz or transitivity quiz, etc, in the grammar section of the study center, the end of quiz page presented the option to study another lesson in the same category, like it does with vocab/kanji quizzes.
Done! The grammar expression lists might list more than what is available for non pro users, but that is because I'm making a change in the availability of renshuu pro lessons in the new version, but I have to wait until the beta is ended to flip the switch! But the lists should be showing up.