The only time that comments should be held in moderation is the first time. Occasionally, the software “holds” a comment from an existing user; when I notice that, I just let it through. That’s abnormal and it is not something I cause to happen; don’t take it personally.
On the other hand, new user’s posts are automatically held for moderation until I approve them. I let them through unless one of three things appear to be so: The comment is clearly spam; or the user selects a name already in use; or the user enters an obviously fake email address. There are two comments held right now under rules 2 and 3 (both unusual); for one, the person selected the name “Ben” and I wrote asking them to change to another name, and for the other, the person (writing a personal note complementing Bill Luckett) entered the email address “email@example.com”. I’ve not let either through, as noted.
At least as far as spam-generation goes, computers are still failing to meet the Turing test. I never have any doubt whether I’m looking at a spam-bot or a person.