The double-edged sword of SRS.
If you can find a sweet spot for the rate at which you add new items, an SRS system will perfectly manage your time and effort, allowing you to make efficient progress in that area while still focusing on other things.
On the other hand, miscalculate that new item rate and find yourself a slave to the SRS system with no time available for anything else.
Faced with the latter, finding room for other study is a choice between a) stopping/slowing new items in the SRS to begin what can be an agonizingly slow, long-term process of decreasing the stream of reviews, or b) increasing your total study time in order to add other things on top of the time the SRS already demands.
The fact that you can’t just say “I’m going to do less of this SRS system today and work on something else instead” (you’d just be adding today’s SRS load to tomorrow, or this week’s load to next week’s, etc.) is (imho) why so many WKers have such a hard time focusing on other areas of study. If you have 25 hours per week to study Japanese, it is VERY difficult to predict what amount of new SRS items will add up to, say, 10-15 hours a week such that you still leave another 10-15 hours free for grammar, etc.
Not to mention: the gamification of leveling up, the community encouragement, and just how fun WK is in general all further incentivize over-committing to too-large a workload by taking on too many new items.
To answer OP’s questions: yes I had the same problem. What worked for me personally was to compromise somewhat in other areas at first until I got to the low 40s on WK. I was extremely motivated to do WK and also believe that learning kanji first makes everything else easier.
But if you feel like WK is taking too much time after doing 10 levels over a year, your situation is probably different. My advice would be to always do all your reviews as soon as they come up, and pick a consistent plan for new items (10-20/day for example), pay attention to the resulting workload (clock your hours if necessary!) and continually recalibrate until you have found an amount of time that doesn’t interfere with other areas of study (or with the rest of your life… whole other conversation…)
Just remember that it takes at least a couple weeks to see the result when you recalibrate your rate of new items. I stopped new items completely at 42, 49, and 51, and all three times it took over 2 months to really see much of a difference at all. You should see a difference faster but it will still take time (and depend somewhat on your accuracy rate).