python celery for every work is efficient?
You have it about right.  You can put whatever processing you want in celery, but the rule that you just used--use celery for things that take a long time--is the one we use most in our production environment.  You can also use celery when you want to scale out an operation across servers more easily.  For example, when scraping a large number of pages, you might want to execute that in parallel to speed up what would otherwise be a long-running task.
I'm making API server with python flask.
In my case, it is real production level, So I have to be careful when developing server.
After google searching, found that celery&redis is suitable for task queueing.
So I installed celery&redis via pip3 install 'celery[redis]' and defined task, and run.
Everything was fine, but I got some question about it.
Assume that there is user model. Maybe CRUD for user model like this.

Register user(with photo)
Delete user
Get a single user

In my personal think, only Register user need to celery&redis.
Because upload photo can take long time, so it have to treated with asynchronize work.
Delete user and Get a slngle user just query to db and retreive it.
So it doesn't takes longer time. (it means, do not need to work with celery)
It is right? Or, any missing feature I do not know?
To summarize my question, I want to know that is there any standard for celery?
Thanks!