Since I mentioned that the TIE Interceptors of the 181st and 128th fighter wings had been reequipped with shields I thought I would clarify why that model and others still doest not bear shields in the various stories that come after the Thrawn Trilogy.
Thrawn was notoriously conservative with his resources and he saw value in everything no matter how old or decrepit it may have been. The Katana Fleet is probably the best example of this; Thrawn committed some of his most powerful assets and a good deal of his personal attention to finding this fifty year old ghost fleet of aging warships to bolster his fleet. When he took power he immediately began equipping the less advanced TIE models with shield so very suddenly the Republic began facing Fighters, Bombers, and Interceptors as well as other previously unshielded models bearing shields. It wasn't a universal conversion and given the cost of converting them only certain units considered invaluable were so upgraded. However, given Thrawn's attitude towards the Empire's policy of expendability—that is to say he viewed it with great disdain—he likely would have made future production lines of the unshielded TIE models come standard with shields provided he had not died at Bilbringi.
There is no record of the Interceptors of the 181st or 128th actually bearing this upgrade, but given their lauded status and ability it would seem rational that Thrawn would pick them to receive this upgrade first of all the units so upgraded.
Sadly after Thrawn's eventual defeat the Empire largely reverted to its prior methodology and very few, if any, TIE models were upgraded with Thrawn's ideas in mind after his death.
Author's Note: The Thrawn Trilogy (aka Heir to the Empire Trilogy) is written by Timothy Zahn and is comprised of Heir to the Empire, Dark Force Rising, and The Last Command. It comes in both novelized form and graphic novel form and I highly recommend it to anyone who loves Star Wars or has read my story and liked the character of Thrawn. There is also a second series of books (sometimes called The Hand of Thrawn Duology) that involve Thrawn more loosely; again by Zahn titled: Specter of the Past and Vision of the Future. Both are enjoyable reads. Most of the events I depict take place before The Thrawn Trilogy however the final chapters take place during this time and I reference events from The Hand of Thrawn Duology as well.