As long-time a 'practitioner' of machine learning models I strongly disagree, the preferred form for model modification is by retraining the model with a tweak to the parameters or the training algorithm or the model structure or data selection or length of training.

You can get some effects by fine tuning, and in that case it may be preferable as it's cheaper, but in general if I want to have a different or better model, that involves retraining.