It's possible to enter just your net pay into Quicken, but I don't recommend it. The reason is that there are real benefits to knowing the total amount of deductions from your paycheck, especially at tax time. You (or your accountant ) can look at a report of all of the paycheck deductions and get the information you need to complete your tax returns more quickly.
If your paycheck varies each pay period, you should still set up your paycheck as a scheduled transaction. You'll be able to enter the varying amounts in each split line without having to recreate them each time.
Paycheck Setup (Mac) p. 36
The QuickFill feature is very useful to enter categories, but sometimes you need a quick list of all the categories to figure out which category you want to apply to the transaction. The triangle in the Category field of a register brings up a pop-up menu with all of the categories. Click the triangle, then choose from the pop-up menu.
Subcategories appear in the Category field separated by a colon . For instance, the Fire subcategory of the Insurance category would appear in the Category field as Insurance:Fire . When typing in the Category field, you can enter subcategories by typing the colon, then the first few letters of the subcategory.