I use a 50mm wide roll. I cut patches about 50x35mm. With a Boretech spear type jag I stick the patches offset from the centre towards the corner. Closer to the corner, the patch will be more loose. Closer to the centre, the patch will be tighter. This is the technique they give on Boretech's website.

https://www.boretech.com/informationcenter/resources/side-spiking

Edit: I am using this for my .308