Dripping is a great way to acclimate with the only problem typically being temperature- doing a long drip of up to an hour is great for balancing out all the differences in salinity, mineral levels, et cetera, but if you have the drip container outside of the aquarium, odds are the water will cool down over that period of time. When you go to introduce the fish into the tank, they're suddenly getting temperature shocked.
Ways to prevent this is to float/attach the dripping container inside your sump, so it's kept thermally stable by the surrounding water.
Otherwise, attach a container inside the tank, and simply do the "add some water every few minutes" approach. It may be a bit rougher, especially for extremely delicate/valuable fish, but much better than doing a really good drip acclimation but ending up temperature shocking those same fish.
For typically sturdy fish, such as non-delicate wrasses (sixline, melanarus, coris), sturdy gobies (clowns, firefish) or other 'tough guys', typically a temperature acclimation can be plenty, depending on the water they're coming from. If your store is running their fish at a lowered salinity, or with medication, try and be aware of these things so you know what change the fish are going to go through. If the fish are kept in a lower salinity system, keep in mind there's more oxygen prevalent in the water they're coming from, so a sudden shift can be extremely challenging in such a case, and dripping is the much better method.
Regardless if it's from a store, or from a fellow hobbyiest, it's always best to prevent water transfer if possible. Not always needed, but there's really no downside to establishing the practice of keeping tanks separate from each other.
