Does size matter when saving OP seed

[mensplace]

Having now looked at the seed from hundreds of varieties it seems that the size of the seed has little to do with the size of the fruit as some huge varieties have very small seed while much smaller fruited varieties may well have far larger seed.

But, within any single variety is there any real relationship regarding the size and plumpness of seeds when selecting from those from one fruit.

With the number of seed possible from one fruit should the size, shape, plumpness etc. even be a major factor in saving for the next year?