That’s true. I don’t personally find it boring doing my HIIT cycle. To ensure you still get full benefit from doing the same exercise, you just need to increase the intensity or resistance which is why cycling on an elliptical is so good because you can put the resistance up when the exercise feels like it’s getting easier.

There's usually many variations of a given workout that allows for a range of effort levels and targeted muscle groups.  You can do a "core set" of exercises yet not do repeats of the same specific exercise for nearly a month!  You want to find a program that introduces new levels of challenges progressively (from a simple and relatively easy version to more complex and challenging as time goes on).  It all depends on exactly what your goals and physical limitations are.