As an examiner of 20 years when I,m presented with a logbook with P1/s in it I treat it as P/ut for licensing purposes unless it was a successfull flight test with an examiner or as co-pilot but handling pilot of a certificated multi-crew aircraft .The CAA are quite clear on this and have been for many years.I was checked out on a friends homebuilt biplane recently and quite happily entered it as P/ut .I,ve got 14000 hours and am still learning every time I go flying!!.Really this is all about egos, having gained a licence some people just can,t bear to admit there is anything left to learn.Most of the time P1/s entries are irrelevant as they can just be treated as being part of the dual allowance however if you were tight on hours it might just tip you over the edge.This one will run and run but P1/s doesn,t get past me when it matters.Fortunately aircraft fly because of the laws of physics and finance not the semantics of aviation legislation!!.
