Personally I start stressing when I'm sending less than 100K clicks a day to affiliate programs. That's when I really have to kick into work mode and get my traffic hustle on. However a lot of that traffic is straight redirect traffic from the serps so the quality is not that good - it's not presold, but there is a lot of it.
One of my mentors back in the day (Richie from MaximumCash if anyone knows / remembers him) told me to focus on nothing but traffic generation until I was sending 50K clicks a day to sponsors. That seemed like a ludicrous amount of clicks at the time but in retrospect it was sound advice.