I believe the centre section on my S2 had been re-fitted as it was glued down everywhere and turned out to be a real struggle to remove without tearing [This is the one piece section that goes over the transmission tunnel and starts more or less under the front of the seats]. It took me about 2 hours. As Simon says the front footwell carpets are a doddle, they pretty much lift out, same for the soft pads underneath them. It was the same story again in my 968 as I decided to do a carpet swap and put the perfect condition front carpets from my S2 into the 968. This time the centre section didn't look like it had been removed but it was another nightmare. The glue Porsche used in those years is unbelievable, not only is it very strong it strings out up to 3 foot long and literally sticks to everything, luckily I don't think they used this glue on 944's. It took me over 2 hours of heaving to get that one section of carpet out and at the end I was shattered. Basically it took me something like 4 or 5 hours to swap the carpets over but I couldn't do the rear of the car as they are different on 968's.
Again as Simon indicates you need to be very careful with the 2 sections of carpet one on each A pillar down by your right ankle. These have a slither of fabric that slips under the door seal and tears very easily, again its a similar story with the 2 small sections one of each in front of each seat bucket. The fabric that slips under the seat base tears off very easily. Others have told me this fabric falls apart anyway and the best thing is to stitch some new fabric onto these carpet sections prior to refitting. I have to do this on mine.
IMHO someone who is experienced with car interiors should be able to completely strip the carpets and trim in a day without destroying it all.