Working on new model, I've got an idea of improvement which may greatly improve productivity.
Point is to allow selecting some default datatypes just from ADD button drop down menu (see attached picture) without need of using on-grid comboboxes which are just slow.
Values shown in drop box should be editable in global config, or projectconfig (in best case both, when project would derive from global settings allowing some changes), Theoretically number of entries may be unlimited, but from my experience 3 up to 5 is enough.
Defaults should contain data type and its size (if needed). It may also define Not Null constraint (which might be shown by NN tag next to name).
I will put it into Idea Pond, but IP doesn't allow to add attachment, so I made use of forum to achieve this