You have asked specifically about "fair" entries at Fairs.
I can't speak for your area, but can share from mine.
At the Fairs, the classes are clearly listed.
Some must be made only by one person. Some allow for a different quilter than piecer.
Some are specific to group efforts, perhaps a block swap or a group that has quilted it together.
Some will be specific to hand quilting. Some machine quilting, but not LA. Some machine quilting for both DSM and LA. Some even leave it open to any type of quilting whether it be hand, tied, LA, DSM, etc.
Some are specific to sizes, eg must be 48x60"
... and others have minimum or maximum sizes stated.
Some give no size requirements.
There are many more variables to the class possibilities. And many different combinations to the above.
What I find the hardest ... is reading the fair/show class info ... and interpreting some of the meanings of the classes.
So there's no reason why you need to feel intimidated. Just do the best job that you can, and with time your abilities will improve.
I will highly recommend to you (and others) ... get out there and show your quilts. It is so rewarding to go into a show and see yours hanging there .... if there's a ribbon, bonus! Many times you will receive feedback that can help you understand how to improve your future quilts. Good Luck!