In this course we will be using one large Photoshop canvas. This course will be presented in text and screenshots.
Pros of using Photoshop
Great if your artwork is all vector
Crop marks can be automatically added upon export
Easily add full bleed
Guidelines are easy to add (you can type in exact values and use math)
Easier to change spine size than in Photoshop
Cons of using Photoshop
Difficult to see placed image scaling
Limited typography capabilities, at least once you've experienced InDesign! At least there are styles, though they don't cascade.
Takes quite a few steps to change trim size (must manually move most of the guides) (but, you can create separate templates for each trim size)
Must crop down an exported image or define slice areas (better option) for marketing images
Depending on the type of work you do, you might not need it nor get as much usage out of it; lighterweight vector can be handled in InDesign also (and Photoshop, to an extent)