My boys are pad trained and outdoor trained. It is handy for emergencies or traveling.
I can take them to visit places, stores or homes, where there is not a pad available and they know not to potty indoors.
However, if you are going to do both ways for potty training, I would recommend always making the pad available in your home, 24 hours a day. If the pad comes and goes, then it would probably be confusing for your pup.
Hope that makes sense. If not, I will try to clarify.
Remember to praise, praise, praise for good potties.