Why do we back roll with a 3″ roller after doing cut ins?  Ceiling cut ins and areas next to trim that are painted only with a brush have a noticeably different texture than the surrounding paint that is typically rolled. To ensure the finished texture will be consistent in these areas, brush on the paint, then immediately roll it out before the paint dries.  I have a video explaining and demonstrating this process throughly.  Check it out on YouTube Paint Life TV.  https://youtu.be/Mb8CFRE2GqE