The thing that kind of stands out to me here is the misunderstanding of some of these numbers. As mentioned by
@Ater it is 4,000 hours... which is a totally different metric than 4,000 views. Do all the sub swapping you want; you'll never get them to watch more than a few seconds of a single video and those 30 views per vid are never going to get you to 4k hours. So that is one of the problems with sub for sub; it does not get you any closer to monetization.
It takes work... both in the research and time in filming and editing as well as the thumbnails, scripting and metadata research (and yes, that is important too... I'll get to why in a moment). But worrying about gaining 150 subs in a single day and then losing a few... that is pittance. 1,000 subs and 4,000 hours is pittance. It may take time... but honestly if you can only gain 100-150 subs in a single day once per month then you are focusing on the wrong thing. Even if they are quality subscribers... and judging by those drop-off numbers they aren't. But I don't think there is a single person here who
isn't aiming for 10,000, 100,000 or 1 million subscribers. And this is just not the way to get there. You need to think big. You need to have a much more global view of how you plan to grow your channel. This is another reason sub 4 sub is nonsense. You just can't sub 4 sub your way to 1 million subscribers and even if you did they aren't going to watch ads and you are not going to get paid. A couple months ago I had to do a sit-down with a channel that had 2 million subscribers and could only get 60 views on a video... the result of heinous sub 4 sub and purchased subs. That is a dead channel, there is no coming back from that. That means that every time they put out a video YouTube shows out 200,000 impressions to that channels audience and they get a return of 60 views. Think about the red flag that this sends to YouTube. Every video they ever post is going to be DOA before it even gets out the gate, they will never get shared out.
You know what helps YouTube to push video impressions? Good video performance. This is where keyword research and ranking for search comes into play. If you make a solid video, and then you do your keyword research and fill out your metadata and this video ranks in search for this topic then you are putting your video directly in front of people who are specifically looking for that exact video. What better way to get positive video performance than by doing exactly this? The better your video performs the more it gets shared out and the more you get seen.
And this is how you get 100,000 or 1,000,000 subscribers. Quality content first and foremost... but get that seen over and over again in front of audiences who are looking for that content. It may take time... but once it hits and once YouTube really dials in on that audience there is no better way to get in front of a large mass of viewers. And as an added bonus until this surge of growth happens you can at least count on getting perennial, evergreen views from these search ranks across your entire library. Give those videos a chance to keep working for you. I guarantee the work put into doing so is inexplicably more valuable than wasting time asking some Johnny-Come-Lately to subscribe to your channel in return for your subscription.