Whirly, I'm with you. I know that you mostly fly helicopters, and you probably recall that I mostly fly microlights. Yet we both hold SEP licenses. The "system" doesn't count either your rotary hours or my microlight hours, at-all, towards SEP currency. Re-arrange this into many variations, the answer is generally the same - the powers that be want to see all the hours, on a specific class, for currency or to do a course in that class.
Does this makes sense, no it bloody doesn't. Why can't somebody flying 100 hrs PA in gliders, SEP, microlights, helicopters, gyroplanes, etc. count at least a large part of that towards currency on another class. Makes little sense to me.
Perhaps we should just bin hours altogether and do everything - currency or proficiency, entirely by test ?
G