I sort of disagree with the bolded. If you think Chase is worth more fantasy points for whatever reason, then those extra receiving yards or TDs he's getting also translates to passing yards and TDs for Burrow or Browning (unless it's Deebo and you're projecting more runs). But I do agree there's wiggle room within this. For my own projections, if QB and WR TDs are within one of each other, that's good enough, for example.
Why can't Chase's increase be to a decrease from Higgins, WR3, and TE's and Burrow stay the same? My point was you are guessing at all position players and if you are trying to make sure all 5 or 6 guys totals are all a zero sum game then you are really putting pressure on the exactness of your assumptions. For me, I would rather go with an initial projection and try and have them match for a team as you are saying but once I start evaluating my tiers and big board sometimes I will move players up or down based on many factors and just because I move Chase up doesn't mean my projections or places for Burrow/Higgins/TE/WR3/etc must move because they are just projections.
The reason being if I miss on my Chase bump up and I move everyone else because of that then I will miss on all those guys too. However, If I move Chase and he doesn't do as I expected there is a chance all those other guys initial projections still hit. I am trying minimize the damage of all my projections if my change is wrong. Like I said, it's all guesswork anyway.