The default Discourse count for consecutive posts is set to 3. We had it changed to 6 when forum launched, and it was reverted back to default of 3 recently. I believe the 3 consecutive posts from one user in one thread is more than enough. This is unrelated to what content one users posts. Either 100 images in one post, or someone decided to quote their favorite pages from Ulysses.
The simple answer: just add things to your latest post, if it is the last one in the thread. If you’re not about doing that, the system will help you re-consider after 3rd post in a row.
Now to the poll. We won’t do unlimited consecutive posts at this forum. I highly recommend checking this manual for Polls for future reference. It is an awesome feature which has lots more under the hood: How to Create Polls - faq - Discourse Meta