how long does it take to drain a full can? Do you sit there pinching the end the entire time?
When I use the it for 5gal or 20L container it takes just a few minutes. I don't have the exact time, but it's quick. I timed it once, but my memory fails me. It can seem like a long time when you are holding the can or holding the tube in the can.
I've only had to use the siphons five or six times for water and gas cans so I don't have a ton of experience.
I use them for water and gas but of course have separate hoses for each.
I have a super siphon or safety siphon and a few of the cheap imitations that I found at my local Lowes.
I was having trouble getting it to the bottom of the can since it want's to roll back up in itself.
One method I've used is to straighten out a hanger or I guess you could use anything long and straight and clean. Then zip tie the super siphon to it so that you have a nice long rigid run that goes all the way to the bottom. I've also used a small hand clamp to hold it to the can lid but you must monitor it in case it slips out. I think it's better to hold it to reduce the chance of an "uh oh" moment.