>>8437572I did it that way so that I can mask in multiple steps, each step being fairly simple and easy to fix or redo. If I did it the other way I would have to mask all white (actually light gray) at once and the resulting mask would be more complex and prone to failure. Something like pic related would have been more difficult to mask the other way. Also, flight deck markings needed to go over the panel lines.
Masking fluid was used to secure the tape and stop it from lifting. You can think of it as an area-effect elastic band.