A tab on one piece makes the piece being joined to it overlay it so you get the cut end of the part showing and an elevated area. A lot of people use joining strips which is like you cut the tab off then use a strip that is about twice as wide as the tab and glue half of it to the back of one piece at the joint then glue the other piece over the other half of the joining strip. That allows both cut ends to butt up to each other and does a better job of hiding the joint. Joining strips are also handy in closing a cylinder or cone.
Sometimes, especially in extremely small parts, a straight butt joint without any tabs is the way to go. Just run some glue along the edge of one piece and then hold the two pieces being joined until the glue sets up.
It does not really matter if you choose to stick with the tabs. Just a matter of choice.
