When I first started WK, I was following Tofugu’s guide completely, and didn’t pick up my textbook at all until level 10. I was probably spending an hour or so on WK daily, doing 10-25 lessons (ten if it was kanji, 25 if it was vocab).
At level 10, I started picking up my textbook, but when I went back to work (I was put on furlough for a month and a half) I struggled to keep up with it. I found it easy to do 30 minutes of WK in the morning, then my reviews during the day, but I dreaded picking up my textbook. I think it was a combination of being tired after work, and also finding WK “easy”, and seeing the progress in a tangible way, whereas working through my textbook is so so so much harder, and progress is less obvious.
Since hitting level 20, I’ve reversed my studying - I do my textbook work in the morning, to make sure I’m always learning and practicing grammar, and then if I miss doing WK lessons in the evening. I probably do 20-30 minutes before work, then I will try to do 10 WK lessons in the evening, as well as my reviews. I find doing reviews at 5pm/6pm, then 9pm/10pm, then just after I’ve woken up at 7am, works well for me. At the weekends, I try to do an hour of textbook work daily, and keep WK work the same.
For 2021, I’ve banned myself from English-language Netflix. I found that I wasn’t really watching it anyway, I was just playing on my phone with something on in the background, but watching Japanese TV forces me to engage. It’s also a way to immerse myself and pick things up passively.
So, to actually answer the question:
20-30 minutes textbook work
~30 minutes WK lessons and reviews
I watch a 40 minute TV show episode maybe every other day
Now that I’ve written it down, that seems like a lot! I always try to do something, even if it’s reading my textbook for 15 minutes, or doing a few reviews (even when I’m hungover!). There’s only so much my brain can take on a daily basis, and I’d rather learn one thing a day and actually keep it, than spend 4 hours and lose half the lesson by the time I wake up the next day.