Remember that shielding and rolling / spotdodging is essentially a game of rock-paper-scissors, with each option being useful in different contexts. For example, if your opponent goes for a grab, spotdodge is your best option because it will beat the grab and you can punish it. On the other hand, if your opponent reads your spotdodge, they can go for a multi-hit or lingering move that will beat your spotdodge. In this case it would be better to shield, since you can neutralise the potential damage and punish it with an OOS option. Sometimes you might want to reposition yourself when you dodge, so a roll is your best bet in that case.
It's a good idea to have another option in neutral, but it's equally important to understand the micro-meta of evading damage. A good opponent will predict how you'll respond to their moves and bait you into doing something they can punish. Mixing it up is a good idea and it's something you will become comfortable with when you practice spotdodging more efficiently.