Say for example each user has their own unique model, say for example a users music taste. Sure I could encode generic features of their taste, but I want it to be truly specific and personalized per user. However, rather than making N different models, I encode N as a feature to my model, (0->N). E.g:
age, eye color, time of day, user_id
Lets say for now, I'm working with a neural network. Thoughts on whether a the user_id would be enough of a feature to produce different results for each user?