I have found too much friction (stiction?) when taping surfaces with a single strip of tape on both the fixed and movable surfaces. It is less when the tape is pushed in to the gap with a credit card, but still more than desirable. One solution is to have the tape stick to the fixed surface only, leaving it free to slide on the movable surface. Build a tape strip with the rear half covered with a second strip of tape, mastic to mastic. Trim to finish size with a straight edge and knife. Apply the open mastic to the fixed surface and allow the blanked half of the tape to bridge the gap between the surfaces. Of course you need to do both upper and lower sides of each flap and elevator, but if done carefully, you gain a net reduction in friction. I had no luck trying to build the tape assembly on the airplane. The half blanked tape needs to be assembled on a clean surface and then removed for application to the fixed surface. I can't detect any leakage past the unsealed tape, because the application on both sides of each surface works like a pair of facing check valves, allowing no flow irrespective of the orientation of the pressure gradient.