I am looking to train a large model (resnet or vgg) for face identification.
Is it valid strategy to train on few faces (1..3) to validate a model?
In other words - if a model learns one face well - is it evidence that the model is good for the task?
point here is that I don't want to spend a week of GPU expensive time only to find out that my model is no good or data has errors or my TF coding has a bug
For face recognition, usually a siamese net or triplet loss are used. This is an approach for one-shot learning. Which means it could perform really well given only few examples per class (person face here), but you still need to train it on many examples (different person faces). See for example:
https://towardsdatascience.com/one-shot-learning-with-siamese-networks-using-keras-17f34e75bb3d
You wouldn't train your model from scratch but use a pretrained model anyways and fine-tune it for your task
You could also have a look at pretrained face recognition models for better results like facenet
https://github.com/davidsandberg/facenet