That's been my experience on Webtoon for about half a year now. I did get new subs, but lost just enough more so that I saw an overall drop of about 50-100 a month. At my comic's height, I had 7,850 subscribers, and just last month got as low as 7,420.
But this month I made the decision to go from 2 updates a month to weekly updates and the loss of 1-5 subs a day started to slow, then after a few weeks, I stopped losing subs altogether, then just this week, in conjunction with my last update, I've actually GAINED about 15 subs. That doesn't sound like much considering I'm sitting on 7.4k, but after 6 months of having them drip away like water our of a tap, it's very encouraging for me.
So yeah, maybe not for everyone, but for me, keeping up with weekly updates could be just the thing I needed, even if you do get the odd 'too short' comment.