Yes — a zig-zag or U-shaped light-trap entry can work for a darkroom. It’s especially useful when people may enter and leave while work is in progress, because you don’t have to worry about someone opening a door and flooding the room with light.

The main tradeoff is space: a light-trap entrance takes much more room than a normal door. It also may not be perfectly light-tight unless built carefully. In many real-world setups, some stray light still gets in if the design relies only on black paint and the fact that light doesn’t bend around corners.

If you use this approach, make the passage deep, and use very non-reflective flat black surfaces. A U-turn design can work better when the legs are long enough. Another proven option is a revolving darkroom door, which can be effective even where space is tight.

So the answer is: yes, a light-trap entrance is practical, but it trades floor space for convenience, and a conventional well-sealed door may still be simpler if maximum light-proofing is your priority.