I'm new to Steem, but I've read the whitepaper, the wiki, and dozens of posts before signing up. I think your target of 20 to 25 votes a day is about right... I do however suspect that the same people aren't always landing on the trending tab because of financial incentives. That's definitely a part of it but it's also that they're the only ones that produce quality content that you might see in  a magazine or major media site. There's a very low barrier to entry to sign up here and unfortunately the number of users that can write compelling content is the minority. Which isn't a dig against Steem users, it's just the reality that producing content that is popular is hard. It's a skill that takes time to learn.