Usually you upload your finished files to many different agencies at the same time.

Some accept, some decline.

The process you are suggesting is how it is done at some high end places. You can send in a full batch of un processed files, their editors pick what they like and then you just process these files, sometimes with specific directions how they would like to have it processed.

But this kind of more personal service is not suitable for the micros.

If you are only uploading to Adobe, which is not an exclusive agency, you are not really using microstock properly.