Good point. I would be worried that different kernels would ripen at different rates based on the genetics of the kernel. Would some types of popcorn pass the milk stage while the sweet corn is still in that stage? I would like to hear from someone with experience. I've always isolated.

Varieties that flower at different times can also be a great way to plant multiple types close together.

I guess that you have a higher chance of random popcorns when developing a landrace with many types with different ripening times.

I have enough space and do not want to experiment in this space, so I'll isolate.