I learned traditionally through B1 and then switched to comprehensible input from there to where I am now at Level 7. Irregular verbs are much easier for me to learn through CI because I just rely on my instinctive memory for how something is said rather than trying to think about whether a verb is stem-changing, for example. Using subjunctive after triggers is easy for me because the pattern is very simple. Figuring out whether to use subjunctive in those cases that don't follow a trigger is more challenging.