Appropriate string tension for the player?

In the recent years, I have receive many stringing request from novice players for tensions above 25lb? 

For instance. One high beginner (aka D-grader in terms of the Commonwealth grading system) was using 27lb. Another, a low intermediate (aka low C-grader or C2-grade) requested for his new racquet to be strung at 28lbs. Yet another - an casual lady player (aka D-grader) was using 30lb??? And so forth. When asked, the startling reason for using such high tensions -  Lee Chong Wei & Lin Dan using 30lbs and above, so a few lbs lower should be right for us???

A coach I know uses this analogy to explain the relationship between stringbed tension and how much strength is require to push the trampoline down to produce repulsion. Think of the racquet stringbed as the trampoline. If you can jump x-meter high on the trampoline (say default=22lb tension), then to reach the same height after the trampoline was set to a higher tension (say new tension=28lb), you need to push down much harder before reaching the previous height again.

Professionals like LCW and LD may require such high tensions as they do weight training and can hit the shuttle at the sweetspot most of the time. The sweetspot is the optimum area of contact between the stringbed and shuttle eg like center of gravity - optimum transfer of energy from stringbed to shuttle. Hence they could push the trampoline down hard repeatedly, with consistency.