MongoDB Performance Tuning with Dex

"Because Dex relies on heuristics that don’t take your data into account"

So if you do take your data into account and create indexes accordingly and have a solid non-changing schema, is there any benefits in using dex? Is it smart enough to tell me that my existing indexes might not be as good as the suggested indexes? or is this considered part of the data that it doesn't analyse too?

Just curious where and when this tool is a lifesaver.

Dex is very cool. Mongo lends itself to adding fields and queries on the fly which has advantages in prototyping quickly, but the flip side is that many queries don't get optimized. Dex makes it much easier optimize later.