The level with the time limit was intended as a bonus level — I honestly didn't expect most players to beat it, at least not until they'd memorized the layout after a bunch of failures. In theory, it's fully possible to complete, but now I'm not so sure.
The levels are procedurally generated (with a fixed seed), and just a few hours before the deadline, I tweaked some parameters (map size and number of bearers, and key requirement) because I was worried it might be too easy. As a result, I didn't have time to test it properly. 😅