I agree lmar12 but it depends on the flats your using & the logistics of the venue?
With TV or studio flats with a flush surface, the tape works well.
I suspect Kim works with cardboard & Masking [paper] tape. Which works, even strips of newspaper, as it is the same type of material & paint will mask the the edge to an extent.
With most hired venues they prefer you don't use any sort of dutchman or fixed sets, which allows them the ability to easily strike or move set pieces. Therefore as with touring sets which are constanly going thru the bump in & out it is impractical.
With me being  super old I druther use soft [calico/muslin, canvas] flats, which have a better surface finish.
As has been suggested here the jionts can be masked by the design & how they are set out.
Also tape can be a pain when it is time to strike & bump out. To me it is like denailing & just as frustrating, ensuring all the bits of tape & sticky stuff is removed finaly.
 Where with bandage/muslin dutchmen they are easy to just pull off completly in one piece, leaving a clean surface.
Also soft fabric flats are easier to repair than that of hard board ones, which can be difficult to fit broken pieces & patch up damage,

All interesting points. We built soft flats (10 total). I need to go back and read the notes about what Gaafa recommends for setting the flats out. Gaafa, did you say to use black tape from the back?

I am still entertaining the idea of dutchmen. I could have the strips painted wall color already and at least assemble several flats together in the parking lot and then adhere the dutchmen. Whats a little glue in the parking lot, eh?

As for the question of where we home school...Ann Arbor, MI. Our drama program has grown incrediby, as far as what we are capable of offering the high schoolers. This year, we have 34 high schoolers in our class and are renting a nice venue with (I hope) a great set. We are producing two straingt plays this school year (Little Women and Pride and Prejuice). We have 3 women that make up the production team (director and all aspects of backstage). Between the 3 teachers (which are home school moms) we have 22 children between us. My entire budget for backstage (not including costumes) is $200. I am going to go over by only $75. The work has been an incredible hill to climb. But, can you tell I am so proud of our accomplishments (teachers and kids together!)?

Thank you, thank you for all the help!!