Heck, you must have a soft beard, mine's only 3 blade and it's getting dull after a fortnight (These days, in retirement, I only shave alternate days).
I don't think that the old type Bitt uses give any worser shave, perhaps more chance of cutting yourself. I always say that if I won the lottery, I'd go to the barbers for a cut throat every day: There's nothing quite like it, but H & S seem to have got to that, although I've been told one in London keeps a separate razor for each regular customer.