As all icon sizes are divisible by 2 (16, 22, 24, 32, 36, 48, 64, 72, 96, 128, ... ), increasing the increment value from 1 to 2 makes it more convenient to get to the intended value.
Created attachment 9695 patch
Yousuf Philips referenced this bugreport in commit 349a2f11481126b79984220ab11f2ed2bf132e86 Increase desktop icon increments to 2 (Bug #16668) https://git.xfce.org/xfce/xfdesktop/commit?id=349a2f11481126b79984220ab11f2ed2bf132e86
Thanks, I also applied this change to tooltip icon size.
After submitting the patch, i did think about that as well for tooltip. :D