My sister-in-law has fruit trees and in some years the weather and the bloom period don't coordinate and the crop is meagre. I pollinate tomatoes by hand until I'm sure they're being pollinated in the usual ways and the same for squash. I have zero experience with peppers. If my tomato seeds are in the same soil in the same location they should sprout consistently - faster if they have bottom heat and more slowly if they don't. Perhaps more slowly for certain varieties. They're not finicky otherwise. I used to grow them in the ground and now I grow them in pots on my deck. It took me several years to find the best varieties for the location (very hot, very sunny), the best fertiliser, and the best pots. But because I'm never sure about the germination rate I sow too many seeds and end up with too many plants. I had so many some years that I turned my deck into a mini-ecosystem which was...interesting. I try not to overdo it now. I have 19 plants this year.