Wow, never knew I have been instrumental in motivating people to play packs. Awesome, WillLem!

Had a watch of the first level Kaywhyn, and couldn't help but think it's possible to save all (except the zombie, of course).
Oh it's very easy to save everyone in Outbreak 1. I simply didn't bother to

I sometimes go for saving everyone if possible, but sometimes I don't. I'm really odd when it comes to this haha.
Feeling inspired by your LP, I also filmed my own quick LP of Outbreak but forgot to start OBS!!! I managed to save all (but the zombies) for the first 5 levels. There are some belters in here! Levels 6 and 7 were particularly challenging. I'll probably do Apocalypse for my (planned) Last Rank LP.
Replays attached 
Nice to know that people here are indeed watching my LPs. I just don't know if the pack authors have. I remember you asked Armani if he was considering to do any LPs, as like you I would love to watch him do them, but as he has said he has no plans to do any in the future due to various reasons. It's not because he said "no" that made me take up LPing. I simply decided to do it after I saw how very easy it is to set up OBS and how I was looking into getting a new and much better laptop. Despite how I fumble my words a lot when recording, I'm still willing to do LPs. So far, with the two packs I have LPed, I'm enjoying myself a lot when doing it, and so rest assured that you will be seeing more LPs from me in the future. That reminds me. If you have any recommendations/suggestions for packs that I should LP, feel free to drop them off at my topic here:
. I can probably take a look at your video series of first rank packs you did for ideas, and I'm definitely considering your packs to LP

Until I get suggestions from people, I'm going to hold back on doing my third LP, since I don't want to make the same mistake of LPing a pack without input from the community, like I did with Doomsday Lemmings.
Yes, you're right in that after the first 5 levels of Outbreak, which are very easy and extremely open-ended, the final two levels of the rank are the most challenging because they're no longer as open-ended, so the difficulty already picks up with them. I saw your replay for Outbreak 5, and I can say that you somewhat made it more difficult than it needed to be.
In my solution, all I do is dig on the left side so that one lemming slips by to be the blocker to turn the zombie around. Everyone else drops into the digger pit, and then once through, bash the wall on the right and that's it.
edit: regarding my complete set of replays, I just added a note to that post saying that if you want to view them, make sure you do it in v12.9.4, as those replays were made in that version of NL. When upgrading to v12.10.0, 4 of my replays break, and the replay refresher tool doesn't fix them, because I apparently played a version of the pack that was made for versions earlier than v12.7, which is why it doesn't work.