@Matt F Based on my experience you can train different forms with a single model and check if it works with the required accuracy. The guidance has been in place to use similar forms for training since the earlier versions of the API and their has been a lot of improvement with the form recognizer models with the latest version that many custom models will work with forms on which they are not trained. But, this cannot be expected for every untrained form because the complexity of the forms might cause some analysis to fail.
You can compose models with the combination of models that best work with multiple form layouts. This can ensure you have maximum coverage without having to exceed the compose model API's limit.
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