Most likely the slow shutter speeds are due to dry oil. You might try soaking the shutter in clock cleaning and rinsing fluids. It's really best to dis-assemble because you will be left with fluid traces on the leaves that will take a while to dry out. These early shutters are not as complex to take apart as the later ones. After cleaning, lightly oil the movinf areas (not shutter or diapraghm leaves) with watch or clock oil (Moebilus).
As to collectibility, yes all Rolleiflexes from the beginning to the 50's are very collectible if they are in excellent condition. But I use all mine from time to time. I have most all the pre-war models including two Original Models (1929-32). I am not sure where some have gotten production numbers, but the serial number range for the Old Standard (all three models) is from 200,000 to 567,000. Some Baby Rollei's also shared those numbers, but I would think the production was higher than the figures quoted, but I could be wrong.
If Old Standard is pretty nice, I would suggest getting another Rolleiflex for everyday use. An Automat type would be a good choice, made from about 1937-50. If you get one that is working, but not all that great cosmetically, you can probably get one for $100 or less.
Hope this is helpful.