I do use it sometimes - I’d say 60% of my shaves I’ll use some form of preshave. Usually right before I start building the lather, I’ll use proraso green. Do I find it helpful with shave - not per se, not enough of a difference that I’ll notice, but it seems like it helps some soaps explode with more lather (again - seems , since there can always be some minor differences in other variants).
Now with the preshave oil - I tend to use it an hour or so before the shave , to let the skin absorb as much moisture as possible and be well hydrated prior to the shave. Apply oil directly pre shave - makes no difference to me - I’d even dare to say makes it annoying since hair tends to stick to razor then lol ! Another option is to add few drops of preshave oil to soap once lathered up and give it a few swirls . On less slick soaps, that can elevate them to crazy level of slickness !
Now with the preshave oil - I tend to use it an hour or so before the shave , to let the skin absorb as much moisture as possible and be well hydrated prior to the shave. Apply oil directly pre shave - makes no difference to me - I’d even dare to say makes it annoying since hair tends to stick to razor then lol ! Another option is to add few drops of preshave oil to soap once lathered up and give it a few swirls . On less slick soaps, that can elevate them to crazy level of slickness !