Tagging the questions by the principle that "as many relevant tags as possible" sounds good, but does it practical with for example facing with the limitation policies about tags usings in MSE?
For example for the questions about improper integrals, when applying the principle that "as many relevant tags as possible" , they should at least all tagged with improper-integrals , definite-integral , integral , integration and calculus . This have already run out the quotas of number of tags using on each question in MSE, so how we can for example adding the tags that showing the additional backgrounds of the questions? Moreover, this is also belongs to "tags-abusing".
So, unless the number of tags using on each question in MSE have no quotas, you can freely tag the questions by the principle that "as many relevant tags as possible". Otherwise, please be cooperate that tag the questions by the principle that "only with the most specific tags that apply". Moreover, for example tag the questions by the tags solely for the OPs' own favourite are also inappropriate, otherwise can we still maintain the community orders in MSE?