Nah, while a few signals might require a 10 foot dish (such as the 16PSK ones) most will come in fine on a 8 foot dish IF you have a modern LNB and IF you have a modern digital receiver and IF you have at least some idea how to aim it, and how to set the skew and focal depth on the LNB. The problem with the hobby of satellite TV is there are a lot of different parts that need to be individually adjusted for maximum signal strength. For example the dish could be pointed dead on at a satellite but if the skew on the LNB is way off you won't see a thing (though you might if you lie to the receiver about the polarity). Or if you have an older than dirt receiver that only receives analog signals you won't get anything. Or if your coaxial cable is bad... well, you get the idea.
I've always had the best luck taking the receiver and a small portable TV right out to the dish and setting it to a known good transponder, then if you get fairly close to the satellite you should start to see a rise in signal strength. If not the LNB skew may be off, or the LNB may be bad (especially if there was ever a close-by lightning strike). In any case once you can receive something out at the dish, if you can't receive it inside the house then the cable might be bad.
Check your local library (don't forget about interlibrary loan) and see if they still have any old books from the 80's about setting up a home satellite system. Ignore anything about receivers, satellite positions, or old-style LNA's because that will all be ancient technology, but concentrate on the part about how to aim the dish and how to track the satellite arc. Without knowing more about what actual equipment you are trying to use (besides the dish) it's hard to make any more specific recommendations.