So far, I've only used it on 1/7 scale. However, the panel lines on full size planes are very small, and I would think the fine line that 1/64" tape makes should be sufficient for scales up to 1/5th or maybe even 1/4. One area of exception might be for simulating the joints of removable panels such as engine cowls. There you might want to use 1/32" just to make them more pronounced than the rest of the panel lines. Accenting panel lines when weathering is what will really make them pop.

Scott