This is a question for drywood termites. In this answer summary,  I’ve left out the product names. I don’t like going to court. “Fumigation” is when they wrap your house and gas it, that is to use a penetrating gas to enter every place that a termite might be. In general, the answer is a simple, no spot treatment ever tests as being as effective as fumigation, regardless of the spot treatment used. Fumigation means that a deadly lightweight poison gas seeps right through your home and into everything, even right into damaged wood. It is used on drywood termites (subterraneans may avoid it and dampwoods are more cheaply controlled). Fumigation is generally thought to be bad for the atmosphere and it uses a lot of toxin. It does have the benefit of usually wiping out every last termite, cockroach, and, fish, pet, that’s exposed. It is the best treatment for drywood termites. It is nearly always useless against subterranean termites because these can retreat into ground when disturbed (but good if they can’t get away, such as in a wooden boat). Whole-of-house heating comes in a close second and is perhaps more environmentally responsible (if the plastics in your house can take the heat). Spot treatments can work really well but the technician has to find and treat every bit of infested timber. There may be hundreds of little drywood termite colonies in the one building. Knowledge of the pest species, locality, needs, preferred foods and construction types is important when making decisions. Borates and other preservatives do have something over fumigation in that they keep working after the wrappings come off (you wouldn’t ever want to be exposed to the  gas residues) and so these provide some ongoing (‘residual’) protection. Bottom line is that it depends on the extent and nature of the infestation and that means that you’ll probably need to rely on a specialist timber pest inspector to help you decide what’s best for you.
All that being said, Don is interested in the clever use of spot treatments for West Indian Drywood Termite in Queensland, where with quality inspection, there is a good chance of achieving effective risk reduction.