Crikey, didn't any of you guys fix your own bicycle punctures?
If you submerge your manifold / lines / QDs in a bucket of water whilst under pressure you will soon see if you have any leaks. If you are really paranoid then leave it there overnight and see whether you get any tiny bubbles forming around the joins.
If you want a trouble-free draught system, the only way to do it is to LEAVE THE REG ALONE! Any time you make an adjustment it takes at least a day (and usually several) for the system to settle and rebalance, you really don't want to be constantly SCREWING WITH THE REG.
If you leave your system balanced, when you hook up a new (uncarbed) keg it will be perfectly drinkable in a day or so and perfectly balanced within a week. If you want to force carbonate then get a second reg to do it, or accept the fact that your whole system will be out of whack for a few days because you SCREWED WITH THE REG.
The trouble with disconnecting the gas every night is that if you have any kegs that are still cooling or not fully carbed, the whole system will try to equalize and lose pressure until you reconnect. This constantly fluctuating pressure is a PITA and means your system will never properly balance - it is the same as SCREWING WITH THE REG.
If you have leaks you will lose gas regardless - so it is your choice whether to lose gas out of the beer and always have a crappy draught system that never settles, or lose gas out of the bottle but pour perfect beer. Or fix your leaks, lose no gas and have perfect beer.
I disagree that it is 'bad practise' to leave the gas connected, I think as long as you check approriately for leaks it is the only way to go.
AND STOP SCREWING WITH THE REG!
:beerbang: