Being on the Recommendation Titles means your series will get shoved into people's face the moment they stepped into the Discover section. Wouldln't that be a counter productive thing to do if Webtoon is trying to foul play you? They could have not featured you at all on the recommendation if they so choose to stunt your growth. From way back I have seen series not gaining that much views or subs despite being on Recommendation or Weekly Round Up too, it just comes down to the reader's taste, I guess.
WIth that said, I do believe Webtoon might in fact has some sort of favoritism when it comes to certain series. If you pay attention, there are some series that keep on appears again and again in "Fresh Pick", quite strange for being "Fresh" but oh well.
In my personal experience, my series is always in either the first or the second spot of Fantasy top 30. But the past few weeks, I haven't gotten a lot of subs or views. I used to gain around 1k subs every few days, but it only happen every week or so now, so on average I'm gaining about ~50-100 or even less subs a day. (Probably counting in the subs losing each day too) Even on update date, the growth wasn't that significant. I believe a lot of series have been experiencing this slowth growth. (Except a few... that is being unintentionally promoted the heck out of like certain Romance series that I saw coughs)
On that note I have only appeared in Recommendation once, sometimes last year, and maybe a few weekly round up. Beside that my growth was and is just a steady ride (even a slow one the past months). Although yesterday, my series got picked to be promoted on the front page banner of Webtoon and that sure lured a lot of traffic in. Though I expect the traffic to slow right back down after I get off of the banner X")