1. A method for model adaptation for a speech recognition system comprising: using at least one processor, determining a performance assessment of the system, corresponding to either recognition of instances of a word or recognition of instances of various words among a set of words, the performance assessment of the system based on a plurality of recognition observations by the system; and adjusting an adaptation of a model for the word or various models for the various words, by making a comparison of the determined performance assessment of the system to a performance assessment threshold and making a determination of whether to adapt the model or various models or whether to withhold adapting the model or various models, based on the comparison.