Any world or olympic class swimmers, or coaches, on the board for some questions about this topic? 
Well I guess no swimmers out there…and I wouldn’t have a clue since rats don’t swim a lick. I fist heard about tapering years ago from a colleague whose son was a swimmer at UofM I think it was. At the time I wondered about the cross applicability between golf and swimming…and the thought still crosses my threshold at times…especially when talking about no warm ups before playing, or even warming up prior to a playoff that may be minutes away or an hour away, or even preparing for a single event in the near future.
I also saw some similarities between tapering and taking tests in school. I know my best test performances on a test weeks away always came from the same formula: study hard, almost too hard, the first week or so and gradually spend less and less time over the coming days until a point about 2 days before the exam. Those 2 days I would go to the beach, or whatever, not studying at all- just to let the brain absorb all it’s been through. When the exam proceeded, I was fully rested, relaxed, but feeling a need to unload a bunch of stuff.
As I understand swimming tapering at a world class level it works something like this hopefully correct example. If the event is 6 weeks away the swimmer may do 500 lengths per day for a week…then 400 lengths per day for another week…then maybe 300 lengths per day the third week…250 lengths per day the fourth week and 250 lengths continues until about 3 days before the event when all training and swimming lengths stops.
Again, my recollection of my collegue’s description of this is foggy so bear with me. But I think the rationale between tapering and the sudden stoppage of swimming lengths causes a withdrawl-like scenario one would see in a drug user. If the abuser lessens the amount of their intake in an attempt to quit, the reduced amount may satisfy for a time, but eventually the cravings will come front and center and cause voluntary and involuntary actions.
So for the swimmer. the sudden stoppage causes his fast and slow twitch musles to crave action and they can’t wait to get into the water- and when they do they unload powerfully and I think makes the swimmer go faster and stronger.
So that was kinda my take on it. I think it would be an interesting experiment to prepare hard for a singular event and 2 days prior to the event put everything away. Go fishing…or relax on Captain’s yacht for 2 days…then go play. 
The principle(s) [of exercise] behind tapering are to do with how the body responds and adapts to exercise. To improve performance the body must be subjected to a workload greater than it can easily do at present. This is termed overload (principle). The body however also needs a period of rest(principle) for it to use food to make the physical changes (adaptations) in the body to enable better performance. Coaches have long known that varying the workload such that a heavy overload is followed by a period of reduced training (taper) can lead to better adaptations and performance often termed super compensation.
One of the reasons I like Lags methods is his desire to have activities be as specific to the golf swing as possible. One of the most important principles of exercise is the specificity principle. That is the adaptations to exercise are specific to the activity being performed. Thus Olympic marathoners dont make good Olympic swimmers …but also within sports a 100m sprinter could not compete with an 800m or 10km runner… each athlete prepares for the specific coordination, endurance, speed and strength requirements of their chosen discipline.
Personally I think for golf the strength requirements dont require the level of overload and hence rest required for a significant taper. However the mental, demands for maintaining technique, strategy and general game play could require “freshening” up prior to play. An important part of a taper focus is the mental preparation side, preparing for the level of effort and demands of competition.
In the past I have used a similar type of approach(periodization) as I use in build up for endurance events. A period of building basic technique is followed by a period of progressively bringing these skills into game situations followed by a period of sharpening game play. Just like endurance sports, you want to time your peak event to be when your game is at it’s sharpest, so it doesn’t pay to extend the sharpening (taper) too long and this is where as in endurance sports tapering is considered as much art as science.
Andrew