They aren't replaced, for instance Saga of Slime and Devil got a new chapter after I spent some time working on other stories. I personally lack the motivation to work on one story at a time, and I fluctuate between them. If I didn't have these other stories, it would just be a few months of uploads then a few months of nothing. The only one I've abandoned is World's Finest Mage because I lost interest in the World's Finest Assassin series
That might be what I do, I have a few ideas, rn im focusing on other things and since I plan to remake it entirely I just felt like deleting it would be better than having people be like 'Update When?' Its on wattpad because nothing I make gets attention there anyways
Theres one consistent rule I have about making fanfics, I do things at my own pace and I write the stories I want to. Spoils of Victory got an update a few days ago if I recall correctly. I wouldn't expect consistent uploads for any one series because I prioritize my own enjoyment over making consistent products. Otherwise you'd get works that I'm not proud of that are either rushed or just not good overall