For me what has boosted the channel has been either the games I picked to play or the topics I chose, often a combination. Some games just didn't fit my content style well, and other times they looked popular but it was actually just promotion hype and the actual YouTube audience was small. I messed with a number of games until I hit one that did much better and I was able to ride that for 3 years + so far. I didn't get the full potential though until I improved my topics and figured out what videos people were liking best.
Breaks definitely killed me at times too. I only uploaded during holidays/summer the first few years because I was at college and just too many people around to record. Then in 2018 I did a 9 month break, that had started with some medical issues but then I decided to pivot my channel and it was just too much too fast for me... luckily I got back to it eventually but it has taken like 3 months to sorta get back some momentum and topics that were good over and over before are still underperforming. I also have not had a single video get suggested heavily since returning where before it seemed like every video I made for a while was getting suggested on all videos in my niche. I'm really making the same type of stuff too, but the algorithm seems to not trust me or interest has changed. The other thing things the hurt my performance were spreading my focus too wide, and uploading more than once per day but I think that varies by channel.