My portfolio is about 3000 photos, but I've got 3 months to shoot now, so I hope to create a good bunch of new quality photos, although I do realise it is alot of work. Plus they might feet in to the summer slowdown so I might not see a huge rise in my income.

Interesting.  Jonathan, it sounds like you shoot and upload in big batches and then have some periods of relatively little activity.  Is that correct?

If so, I wonder how that would stack up against someone who shoots and uploads consistently about the same amount of images every week or month.  

Most of us have seen that we can sit on our laurels for at least a few months with relatively little drop in sales.  I wonder if flooding the market with a thousand or so images after a relative dry spell would be likely to produce a big bump in sales, where just uploading the same images at a rate of 30-50/week would go unnoticed by buyers.

Shooting subject matter at a certain time isn't going to influence when it's needed.  Sure on some of the sub sites, designers might download a file just because it's there.  But for the most part, I think if they need "an elephant perfoming in a circus in spring", they're not going to download something else because someone uploaded a lot at one time.

Shooting subject matter at a certain time isn't going to influence when it's needed.  Sure on some of the sub sites, designers might download a file just because it's there.  But for the most part, I think if they need "an elephant perfoming in a circus in spring", they're not going to download something else because someone uploaded a lot at one time.

You are right, timing is probably irrelevant for a niche subject like an elephant performing in the circus

However I was thinking more along the lines of popular subjects (business, medical, etc.) that are searched for and bought in large numbers every day. 

A lot of buyers do "browse recent" or search by age, not to mention that at times the default search engines at various sites have been known to favor newer files.   In such cases I would imagine that having hundreds or thousands of images recently uploaded could attract a lot of sales. 

Again, I don' know for sure.  That's why I am hoping someone who actually has tried doing it that way would want to comment. 

Just one great picture can double or even triple your sales...

[...] I would imagine that having hundreds or thousands of images recently uploaded could attract a lot of sales. 
Again, I don' know for sure.  That's why I am hoping someone who actually has tried doing it that way would want to comment. 

I consistently see a significant - and lasting - increase in sales when I upload a few hundred pictures in a few weeks following a trip.
Last summer I travelled to Germany (Duesseldorf - Koeln - Berlin - Dessau) and after an year those pictures are still selling well.
It's quite nice to know that I can repay my holidays in 3-4 months and then start earning, makes me wanna travel all the time.

But I never tried to upload such pictures few at a time, so I can't compare with an alternative scenario.