Users may request assistance or information from a limited number of resources, such as submitting a user request by speaking or entering text. A user request from among the pending user requests may be selected using a selection model. A selection model may process features relating to each of the pending user requests and generate a probability distribution for the pending user requests. A user request may then be selected using the probability distribution, such as by making a random selection. The selection model may be updated over multiple time periods by computing reward scores for the selection decisions made by the selection model and using the reward scores to update the parameters of the selection model.