I think regular uploads are more beneficial. But, of course, not just one image, but at least 5-10 per day.
In this case, the images are �smeared� throughout the Adobe portfolio and there is a greater chance of some images getting into the best match.
This is especially true for uploading series of similar images.

From one series, or different images?

If it is a series it might be beneficial to spread them out. Because they then arrive with a different time stamp and maybe one of them is easily visible Monday morning 10 am if the search is set to newest.

Whereas if the entire series arrives Friday night, then by Monday morning it will be pushed back against the fresher content.

It is not an exact science, but if you have a larger series, consider uploading them on different days for better overall exposure.

One a day is better than nothing, but 5-10 a day should be minimum if you seriously want to make money.

If your lifestyle only gives you one afternoon or evening a week to process stock files, you can process 20-30 files and then have enough content to upload every day of the week.