Performance for Large Number of Repeats

1. What is the issue? Please be detailed.
I'm wanting to entirely restructure a large form that I'm currently using for tree observations in a way that would increase repeat count substantially. Currently, my workflow involves a specific type of survey a couple times a year. For these "bulk" surveys, I would like to make my form as quick/efficient as possible for the enumerator and they are almost always identical series of questions for each tree/plant.

Based on my current form, I have one submission for each tree/plant, but I want to try to make the entire tree/plant observation into a repeat group. I could have a couple hundred repeats submitted at one time (likely to be in the 100-500 range for an entire farmer's field). Each repeat would have up to a couple dozen questions, including image questions. Each repeat would likely have a maximum of 3-4 photos and a minimum of 1 photo.

So my question is, does anyone have a ballpark for the maximum number of repeats that could be done in a single submission before things start breaking in ODK Collect? Even if I designed this new form with these large number of repeats in mind, it would be easy to limit repeats to only 10-20 (having an enumerator do a single row/section instead of the whole field) or so and then restart the entire form again.

Does anyone have good reasons why I shouldn't design a form this way? One reason I could think of was that it could be more difficult to track down a single observation that needed to be edited later on.

Hi Tyler,

I just checked, with our most generalist form with two repeat levels, on 17000 submissions over the years, 35 submissions have more than 300 repeats, 15 with more than 400.

What was the approximate size of each repeat? For example, how many questions, how many media questions in particular? I just trying to figure out how much data could be in one submission before it starts getting problematic.

18 questions for the "place" repeat
and 60 questions for the inner repeat (observation) 1 media (photo) max per repeat.