Originally Posted by jcaudill
That's not a rule of thumb I'd follow. Sounds like a waste of tubing and cleaner. There are formulas for a reason! And simple ones at that.
It's not really a waste of anything. That's a negligible difference in cleaner usage (what, a few mL?) and the extra tubing is being used to balance the pressure. If saving a couple bucks on tubing is more important to you than properly dispensing beer that you've worked hard to make, then that's fine. But there have probably been hundreds of posts on here confirming that 5' of 3/16" beer line is simply not enough, and probably 95% of problems with continuous foam go away when a 10 foot line is swapped in.
The formulas are based off a lot of assumptions that are simply not relevant for home kegerators. The resistance of beer through tubing (psi/foot) is highly dependent on both temperature and flow rate. If you're serving a keg at 34 degrees and you need to pour a pint very quickly (commercial scenario), the calculators are good.
If you prefer your beer closer to drinking temperature (~40 degrees) and pour rate doesn't matter, the calculators are now irrelevant. You have to go off the empirical data from the hundreds (thousands?) of us that have gone through this already.
I'd say most of us here have 8-12 feet of 3/16" tubing per line. I have 20 feet of 3/16" barrier per line. Indeed, the general rule is 1-2 psi drop per foot of tubing. It's better to err on the long side and assume 1 psi/foot. It's been said many times on here, but the only downside of longer tubing is a slightly slower pour
Since most of us don't run a bar, and our bottom line isn't a function of the number of beers we can pour in an hour, it's well worth the flexibility to have longer tubing and be able serve a wide range of carbonation levels.
And yes, you certainly can ballpark it. Are you going to remove tubing because you want to serve an English ale with a lower carb level? Or add tubing when you serve a saison? Just leave the tubing longer than it needs to be and wait the extra 10 seconds to drink a beer.