Fuel system

I was just wondering if all of those fuel injector cleaners and other things you just add with gas are worth anything of if they will gunk stuff up?

i use total fuel system cleaner about every 5000 miles, i figure i cant hurt anything...

i use fuel inj cleanor everytime i change my oil

If you use that shit every oil change like the guy said you run the risk of messing up your o2 sensor faster way faster.