And as I explained in my videos, there's where your mindset is totally wrong. Both polishers compliment each other. If I had to choose just one, it would be the PC because it is more versatile. It may take longer to fix really bad damage but at least you can use it to do everything, including spreading wax. Not so with the Flex.
Also, you don't wait until "once or twice a year" to address your paint issues. That's like trying to save water by flushing once or twice a month. You're going to have a crap load of funk on your hands. You address damage as it happens and thus, it becomes very easy to deal with because you are always on top of it. That's what I like to call preventive maintenance. By doing so, you also perfect your technique when it comes to fixing your paint. Don't allow your paint damage to build up over time, manage it (because if you drive your car, the damage will come daily). If someone uses their polisher once or twice a year, I would question why they bought the thing in the first place. You would have been better off paying someone else to fix your paint.
For as much as the Flex cost, I would get a heck of a lot more use out of it than twice a year.