Dado Vucak those results look pretty consistent with most of the markets where I've worked.
As for a parcel being too small, it totally depends on the required setbacks and the norms of that market.
In places like Chicago or Boston, parcels can be very small and houses can literally touch each other (so, parcels don't need to be big in order to be valuable) but if you're talking about a rural market (which I'm assuming you are), again - the setback requirements play a big part in this.
As a general rule, I usually don't look twice at parcels smaller than a quarter acre. That's not to say smaller parcels than this are never worth pursuing (again, there are many other variables that can give a smaller parcel value, like it's location, uses, zoning, setbacks, etc), but statistically speaking, the ones that prove to be worth the time and trouble are typically larger than this.