I think it's important to try our best at giving good advice. It's up to the people asking the questions to decide what's best for them and their pets. But, one of the things that makes this site so successful is that people take the time to offer up good advice based on research, knowledge and more importantly experience.

In my personal experience keeping fish happy is the key to a successful tank. In my experience if a tang is not happy he/she will get ick and most likely die if the problem persists. Keeping a tang in a 29 gallon is by no means a good start at keeping it happy. I'm sure it will work for some...but it's not good advice to advise someone that it's acceptable to keep a tang in a 29 gallon for up to 3-4 years.