A couple more dumb questions

First I'd like to say thank you to all the people on this subreddit. I am learning and people here quite generous with their information and in tolerating my lack of it.

1. As far as I can tell, there are now thousands of varieties of marijuana. I have no ability to keep track. In addition, I have tried different samples of marijuana that has the same name but very different results, strengths, etc. so my question is what's the point of having zillions of varieties, when you can't tell what the "same" substance is going to do? I guess that's why people buy their seeds from the more reliable and long-lasting suppliers.

2. So far, I've been very lucky this year in my grow. My sativa dominant plants are taking quite a while to finish the flower stage. Something is happening that's never happened in my few previous growth. There are so many flowers along the length of many of the major branches that they are melding together into one long kind of bud. The previously I've only gotten small clusters that form sometimes a kind of conical collection. The question is do such long and dense collections require longer to dry or different processing?