I have seen comments that the power supplies are designed for continuous use not regular power cycling. And ADSL Max will behave better as well.
I can't really refute what HPsauce is saying here, although my personal view is that any electrical component that is not designed to tolerate power cycling is badly designed. Nevertheless, any form of power cycling constitutes some form of wear and tear, in physical terms with regard to the power switch and temperature cycle fatigue for other components. Some materials/components may also degrade from continuous operation even at their design temperature.
I've seen other opinions on this forum which suggest that regular (i.e. once daily) reboots should not affect ADSL performance. I tend to only power up my router when I need to, leave it on for the rest of the day and power off overnight. Having said this, my connection performance can be described as variable, although I have yet to determine if this is due to the way I operate the router.
My personal experience is that the responses to queries on this forum are generally accurate and extremely helpful, and it is clear from reading this thread that the consensus view is to leave routers powered up 24/7. On this issue I remain undecided.