Will test only cycles continue to be effective in the long run?

Let's say if I start at 400mg/week for first cycle and don't ever want to exceed 5-600mg/week.

Don't feal like I want to do other compounds than test or test/deca . Is this a good argument to start with low doses like 300mg/wk? How much would I need to up the dose the next time? Would only 50mg be noticable?