A rule of thumb we were taught is half the food comes from training (not to the point of cruelty, adjust the training to be easier if needed so they get enough). You can adjust per dog, but many people treat training rewards as "treats" which are surplus to their needs, so greedy or food-loving dogs (I would be one, as is our first dog) will take it but others won't care.

High stress or emotional arousal or a distracting environment will supersede this but it's a decent starting point which people often miss. Luckily our second dog likes play and praise so that gives us more options.