That is not quite correct. You are confusing the area of the seating surface with the area based on the valve diameter. Let's say you have a poppet valve 1.00 inch in diameter at the seat (neglect the width of the seat for a moment. This yields an area of 0.785 sq. in. This is the effective area of the valve. With the valve closed, the force on the valve due to pressure is F= P*A where A= 0.785.On "Wide versus Narrow seats". The Engineering is so simple that having learned it as a young-un, I believed everyone knew this: The pressure of the seal must be greater than the pressure of the fluid, for the seal to work. As you have a fixed spring on the valve, say 1lb. and a fixed area of seat - say 0.01 sq. in. the pressure it will seal is 1lb / 0.01sq.in. = 100psi. But if the seat is wider, - say an sealing area of 0.1sq.in. - then the pressure it can seal is 1lb / 0.1sq.in. = 10psi....
In other words, twice the width of seal is half the pressure it can take, or 10 times width of seal is 1/10th the pressure it can take.
I'll let you have a think about your valves and springs and then tell me that "poppet valves have pressure helping them seal"...
OK It is a bit more complex, but your experience of "narrow seats sealing better" is the simple solution. And "proper Engineering" is that simple. Solving problems. Which is what you did to overcome your "crop-circles". (But you do need to use a bit of brain).
It could be argued whether the effective area is calculated using the inner or outer diameter of the seat. A "perfect" valve and seat contact would suggest the effective area be based on the inner seat diameter. Since nothing is "perfect", the effective area would be based more toward the outer seat diameter.
Of course the width of the seat does affect the unit pressure of the sealing surface, and narrow seats will have higher conformity and thus better sealing potential.