first a bakery isnt a vanilla building. so if it is not a vanilla one, then it is from a mod... probably <abbr title="Colonial Charter">CC</abbr>....
you would need to have their template first, and it is possible even if you succeed to make a mod to change the number, if the graphic 3D file doesnt have 4 different use dummies inside (use_001 use_002 use_003 use_004 dummies) it is very possible only 2 of your 4 workers will work and the 2 other will wait a free use_00x before going and will idle.
