Depends on how much you shoot and how concerned you are about accuracy, as well as avoiding pitting in the barrel. My father cleans his hunting rifle once a year, with the random patch for drying out a soaked barrel, that's it - shoots about 40 rounds per annum. It shoots sub 1" with norma factory ammo all day long (Tikka), and has done for the last 30 years or more. However, I bet that it has some pitting, and that at some point accuracy will start to deteriorate fast,,we'll see.
My approach is to patch out every 25 rounds to avoid build-up, and to give a big clean every 6 months or so, to avoid long term pitting issues. I think leaving it uncleaned can work for x amount of time, but eventually it will give up, whereas a barrel that's looked after can last a lifetime. Why 25 rounds you ask, well, that's just a number I picked out of a marine scout sniper training manual that I was browsing through for fun, and if it's good enough for them.....why every 6 months for the big clean...well, I feel with the amount I shoot that's 'probably' about right, ie. around 100 rounds.
just my process, everyone will have their own,,BUT, there's NO chance you'll find me scrubbing out my barrel after every outing or so, not only is it way over the top, but it would drive me crazy!