There are different priority levels that you can choose for your plan to watch. Making use of them might help you organize within the list (not that I have taken my own advice, lol). I see that you have already done a bit of that, so you must be aware that it's an option already.
Also, you can make as many custom profile lists as you want (separate from your main list), if you would prefer to keep your plan to watch smaller. Then you can track other dramas you might want to watch by category, theme, whatever you want and they'll be there whenever you want to find them again. You can set those lists to public or friends only, if you worry about random people judging your excessive list-making :D I see that you have a custom list already, so you must also know how they work.
Basically, there are a lot of options, and everyone does it a little differently. But try some things and see what works for you.
I try to keep my plan to watch down a bit by only adding things I feel like I could realistically get to fairly soon. (I have probably failed, even so.) Like, if it's an old drama or movie and I can't find it with subs by now, it doesn't go on the list. I'll probably never be able to watch it anyway, so why put it there? If it's only available to watch on some shady virus-spewing streaming site or something like that, it doesn't go on the list either. I do some research about how I would actually accomplish watching things before they go on my formal plan to watch list.
I try to think of my plan to watch as the thing I consult first when I want to start something new, and I don't want to be totally overwhelmed by it, so I can understand your desire to not let it grow to an uncontrollable size.
