Pierre,
I do the same thing, and a lot of us do - but...
Watch out for insurance to rear its ugly head. IF you are just borrowing the airplane fom a friend, then, as a "permissive user" you are extended liability protection by your friend's insurance policy. IE if you hurt someone, and they sue you, your friend's policy will defend you and pay on your behalf. The policy language makes you an "insured."
BUT - as a third party pilot, the insurer can hold you responsible for damage to the airplane caused by your negligence. Essentially, the insurer has the same rights to come after you that your friend would have. Your friend might not sue you if you damaged his airplane. But, if he turns in a hull claim, the insurance company might not be so forgiving.
Real flying clubs set up insurance with the club - some type of corporate entity as the "Named Insured." Each club member, then is a part of that owner entity and thus protected by the policy and protected by the hull coverage as well.That's the correct way to set up real flying club insurance. And that's why it's relativly expensive. Near commercial rates.
I've seen a group of guys get together and call themselves a club. One guy buys insurance as if it's his airplane and adds all the club members as pilots. They split the cost of the insurance between them. All's fine until there's a claim. Then the at fault "club" member finds himself with being persued (subrogation is the word for it) by the insurer to pay for the damage.