I travelled for eight hours to interview for a contract position which was filled 3-4 weeks ago (guy just started).
I am well aware that some companies keep interviewing constantly as a way to motivate their employees, especially during market downturns. I am sure that it does keep labour costs down, but productivity is likely going down as well, which was evidenced here by the need for expensive contract resources to patch up BAU work.
In conclusion – if you see red flags during application or initial screening process, expending any costs to move forward to final round is probably not worth your while.
Good luck in your job search and be vigilant.