It all depends on how good you are at marketing.
I've had 60%+ on Google ads for a very targeted campaign.
I've had poor CTR on a focus keyword but excellent conversions on a long tail.
If you can get in the mappack, be top in the organics and be running adverts your combined CTR can be fantastic. But do you really need all these leads? You many only need one or two calls per day for fence staining so adjust your marketing according to your needs.
And think about this. CTR isn't a good measure of your marketing. It's quality leads you need. Parking your wrapped van outside the clients property and pushing leaflets through the neighbors doors could be a far better way to get leads. If you can get them to talk about you on FB again this can be a really great source of leads. Being top on Google is nice but niche marketing is often a much better way to spend your spare time.