You don’t Have to dress candles, but you shouldn’t need to dress any candle more than once.
Dressing candles are an especially important part of my own cultural practice as it solidifies that specific candle to the attuned desire and/or connection to the entity. I only dress my candles once and that’s what they will be for from them on, and use the remaining oil i made for burning or to dress new candles when Ive burned the old ones up. It helps some things manifest quicker, and for some entities it’s a personalized honor.
I use oil I made and blessed with the attunements and associations of the planets to address planetary spirits, I have special mixtures for Malphas, Astarte, and other demons, for example, due to working with them often. Usually I have just one specially dressed candle in honor of that entity and multiple undressed candles for the energy. Some do have multiple dressed candles, as personal choice to showcase the strength of the relationship.
Dress your candles if you want to, but no need to redress them, neither with the same mixture nor especially not with a different one.