I wrote up a very long post about my current routine here, haha. I definitely don’t claim to be doing this the best or most efficient way, but in terms of figuring out a routine that I can sustain for a long period of time, and which allows me to make constant, consistent progress, I’ve managed to succeed. So I’ll try to give advice that is more general and applicable regardless of your individual study plan.
One of my biggest tips is to add new resources slowly. My routine probably looks super intense to a beginner, because I’m juggling three SRS (WaniKani, KaniWani, Anki), as well as a textbook and then other side reading projects, but it’s really important to note that I settled into this routine over a period of almost a year of consistent, daily study. I didn’t start out with the full thing in place. I started with just WK, discovered KW a few levels in, added Anki when I started using my textbook (purely using it to SRS textbook vocab only), and then only started mining words from other media at the end of 2021, many months after I started WK.
If you do add new resources, make sure your current routine has stabilized, first. Especially with SRS. You’ll probably feel a bit of a strain whenever you try incorporating a new habit, so you’ll want to give that time to settle, and if the feeling persists, maybe consider dropping that resource or scaling back on other stuff. Basically keep an eye out for signs of burnout, and when in doubt, reduce your daily workload.
I’ve had a fair amount of success tying my progress to my WK level, in that I try to complete at least one textbook chapter before I level up. This helps encourage me to keep pushing myself and progressing without a SRS forcing me to do the exercises. It’s also nice to have different things to work on besides SRS.
If you do go heavy on SRS, be very, very careful about not overloading yourself. I’d recommend against going full speed on WK unless you truly have an ungodly amount of free time and a huge stamina for studying a lot of hours each day. Your WK workload will gradually increase over time, so make sure that you plan for this and accommodate for it with your other study plans. Doing two or three SRS at once can be very punishing and can add a lot of strain, so you have to be careful not to burn yourself out by adding too much new material each day. Missing just one day can be enough to knock you out of the habit completely if your reviews pile up too much.
Because of that, you’ll want to plan your daily workload for what you can get done on a bad day, not an ideal one. With SRS in particular, you’ll want to be able to get at least your reviews done every single day, no matter what. This means even if you’re sick, if you’re super busy, if you’re on vacation, etc. Because you’re going to have days where studying is the absolute last thing you want to do, so you’ll want to make it as easy as possible for your future self to keep going on those days.
I think it’s a good idea to have a minimum daily workload (basic SRS maintenance), and then if you have more time/energy on top of that on any given day, it’s best to do types of studying that won’t add to your future workload, like instead of doing SRS, spend time on reading or watching media, learning to write kanji, studying grammar, etc. On low energy days, you can just complete your SRS reviews and call it good.
Learning Japanese is a multiple years long process, so you’ll almost certainly have things come up in your life that occasionally make it difficult to study. From what I’ve seen, usually it’s unexpected real life stuff that causes people to burn out, so it’s best just to plan for that possibility when considering your daily routine, and make sure that your daily workload isn’t wearing on you too much. Everyone has their own limit here, and it’s okay if yours is less than others’.