Tegaderm is a wound dressing, not a scar treatment so it will not have any effect on improving scars. A silicone based gel or silicone sheets plus pressure are the only things that have any evidence to support them. I’d suggest booking an appointment with your surgeon to discuss your concerns and see what they recommend.
I try to use as few dressings as possible as I have seen allergic reactions to so many products. In general, scarring is a product of genetics. Some people are good scar formers, and others are poorer scar formers. I always minimize the scars to minimize the likelihood of poor scars. There is no one best therapy for scars. Silicone sheets, Mederma, and Bicorneum are reasonable and popular options. I recommend that the scar therapy begin after the scars have healed and there are no open areas, which usually takes 4 - 6 weeks.