BoeingBoy

I can't give an exact ratio of pax/row# but generally yes. Blocking a row at the CG would have no effect (except the new CG because the passengers were moved) while blocking the row that's the greatest distance from the CG would have the largest effect.

If you think of a plane being an arrow - the CG ahead of the feathers (tail) - it'll make more sense. Put an arrow in a bow backwards - feathers in front - and it won't fly straight. Having the CG in front of the controls (the feathers) adds stability. The further the CG is ahead of the controls, the greater the stability. However, you can also have too much stability if the controls don't have the authority to overcome the stability. You push the yoke forward or pull back and nothing happens. Thus airplanes are designed to have the CG within a certain range, usually measured as distance from some reference point like the nose. As long as the CG is within the design range the plane is stable without being too stable.

The last thing you want is for the CG to be so far aft that you run out of control authority to keep the nose up (or down) - the pitch moment of the elevator works through an arm whose length is measured by the distance to the CG. As the CG moves aft, the weight of the forward passengers exerts a greater pitch down moment because of a longer arm while the elevator exerts a smaller pitch up moment to counter the passengers because of a shorter arm. Because jet transports are designed with movable horizontal tails (based on findings in the X-1 tests), that movement can be used as a form of elevator input.

Remember the Express turboprop that crashed on takeoff from CLT a number of years ago? That was a combination of CG being aft of limits (due to the assumed passenger/baggage weights in use at the time) and bad control cable rigging which resulted in not having the full elevator authority. When the crew pitched up to take off, the CG problem caused dynamic instability which caused the nose to keep pitching up and the control cable mis-rigging reduced available elevator authority to the point that the crew was unable to stop the pitch up. The plane stalled and crashed, killing everyone on board I think.

The second worst situation is to have the CG so far aft that in the pitch axis the plane becomes dynamically unstable but is still controllable - if something causes a pitch up or down the effect gets worse as the pitch increases or decreases and elevator input in required to return the nose to where it should be. I made one flight in a DC 3 (a former life) where that was the case and it's a handful requiring constant attention.

So it's important to keep the CG within the design range. Which apparently has nothing to do with the OP's experience.

Jim