Neither really seem to be an issue. I've never worried about fleas, and don't know anyone that has had an issue with fleas... even at work, the only case of fleas I've seen was on a feral cat that animal control had picked up.
Ticks, I suppose it depends. It seems like some people have a huge issue with them, others don't. Me, I've never had an issue with them. Even just on MYSELF, I've had friends that complain every time they go in the woods they have to pull ticks off themselves when they get home. And I'm just like, that's disgusting lol I've never found a tick on me. I have pulled a total of 2 ticks off Juno. None of my other pets have ever had one.
I use preventatives sporadically. With a short haired dog, I figure it's just easier to look her over and pull them off. Guess we'll see what ends up happening with Happy.