In case Windows ever decides to increase the partition size, it also has to change an adjacent partition. The safest way to accomplish that is to keep the recovery partition adjacent to the Windows partition. I'm not sure if there are currently plans to change the partition size, in 8.1 they suggested having 50MB extra in the images partition, the sample scripts for Windows 10 use a 500MB partition for about a 200MB file.
The size could make sense if it's saving a backup of the image when updating which would require the partition to be at least x2 the size of the WinRE Image plus some but at least right now there is no documentation available to understand how big the partition really has to be so the value 500 is all we got.
I missed that also. I was too busy looking at the walkthrough to read it all. I guess I have to go back and read everything. For some reason DISM isn't letting me use the /compact switch and recovery isn't working. My copy of WinPE is from 8.1 Update but I'm using DISM from 10041, I'll try making a new copy of WinPE from the 9933 ADK to see if that helps.
When I tested a /compact install on that tablet I used a bootable USB drive with the 10041 files on it. Started the install, choose my language and then at 'Install' screen opened a CMD Prompt and used Diskpart and DISM from there. Worked fine (surprising quick actually) but I didn't try any recovery partition stuff.
So I made a recovery drive (recovery only, no image) from 10049 and used it apply my customized 10041 image (I haven't built a custom 10049 image yet). I used the sample scripts, just adding in the /compact switch. The size is almost as good as with WIMBoot but recovery still isn't working. I'm kind of interested to know what happens to my customizations when recovery occurs. Or if it will be possible to remove the bloatware packages from OEM installs.
Finally in build 10122 the medialess recovery is working. On recovery I noticed that all customizations were lost but it did retain the product key, updates, and drivers. I wasn't able to successfully create a recovery drive (it always failed to create the reconstruct.wim file) but the $PBR_Diskpart.txt had a few interesting details. The "Recovery" (R partition is now the "Windows RE tools" (T partition. Despite the fact that my original partition was 300MB it was now allocating 450MB.
If you want to keep customizations you will need to look into Provisioning packages via USMT (scanstate), recovery images are not fully supported in W10 for the reset/refresh option, you can only use the recovery image when you don't boot inside Windows but this has a pretty cool side effect as the customization is all in one file, you can decrapify any W10 OEM PC very quickly I don't know if the "remove this provisioning package" is supported for these but if not you can just rename or delete the package and do a refresh and voila signature edition.
I know exactly what files and registry keys are needed for my customizations. Is there a cleaner way to create the package than with USMT?