For riders who use their bikes regularly, Pro Link works very well. People racking up steady mileage tend to pay more attention to regular maintenance, whether they plan for it or have it forced on them by the wear and tear of regular riding. If they don't lube their own chain, I will probably see their bike often enough to take care of it for them.
To do a good Pro Link application, a new chain should be cleaned with citrus solvent to remove factory grease. I dry the chain and hang it so I can drip Pro Link on one end. While I go on with other repairs on the bike, the lube has a chance to spread down the length of the chain with much less waste than if I dripped it onto the chain already installed on the bike.
Repairing a bike with a usable chain still on it, I might get lucky and find it has a quick-disconnect link. This will allow me to pop the chain off for cleaning and lube. Otherwise I can just drip it on the regular way.
I have developed another system for riders who neglect their bikes. If I see the bike has been left to rust, I know Pro Link's light consistency won't hang around long enough to stave off rust for all the months the bike will sit out in the weather.
Lubing for neglect, I leave the factory grease on, and cover it with a heavy application of Pedro's Syn Lube or similar heavy oil. I will still hang the chain and drip-feed it from the top. I will not remove excess oil from the chain when I install it. The chain may turn into a black mess over the ensuing months, but at least it will continue to flow through the drive train.
I prefer clean lubes, but they require more attention from the rider. Neglect a chain with too little lube on it and it will turn into re-bar. If you want it clean, remember to check and renew the lube as often as it needs it. If you give it to me all squeaky and orange, you'll get gooberlubed.