I've only got contracts in place for a very few of my jobs. One was for one year (quarterly cleans) but has now become a second year with the likelihood of it becoming ongoing. Another one was quarterly ongoing but a new manager came in and wanted to chop the price to ribbons. We didn't reach agreement so that one stopped. Another is, again, quarterly and ongoing. Those are all written. They would probably carry no eight in law. They are simply statements typed out by me of what I am supplying, for how much, and what notice would be required by either party to terminate. They are signed by both parties.
I do a bit of commercial subcontracting from several companies without written contract. I'm OK with this as I know the owners personally. Not a guarantee of course but I feel OK with it.
I have other commercial jobs that are verbal only - including one fairly large one. That may sound odd but I'm OK with it.
I even subcontract a shop for one guy who I have never met. He phoned me up three years or so ago. We agreed a price on the phone. I invoice him once a month for weekly cleans. He sends a cheque. Occasionally a payment might lapse and I get two the following month but that is unusual. I sometimes wonder if I've ever met him without realising

.
Perhaps I'm a bit too lax with the written contract stuff but I generally show a certain amount of trust until it gets broken. Once it is broken however, it would take a lot for me to give a second chance.
Although it could hurt a bit if I wasn't paid from some of this work, I never allow enough to be owing that would cripple me.