I don't use an extra sheet of paper, but the transfers are about 95mm high on a 10oz mug minus my trimming.

The actual oven temperature can vary according to the Salter thermometer, but at present it reads 160 degrees which is the same as the dial. 19 mins for 10oz AAA Orcas. 1-2 mins more for designs with large areas of dark green. In total I'll print 14-18 mugs per batch. I reload the oven immediately.

What paper and ink are you using?