Unfortunately they weren't all that good at it. Take a look at deflector shields for example:

In the Han Solo and Lando Calrissian tales from the 80s, shields were a support layer within the armor plating of the ship itself and provided structural integrity for the ship as it pulled high-G maneuvers. This was an early attempt to explain why shields are never shown absorbing damage in the movies, the shots always hit the ship itself. This was prior to the existence of the lore authorization committee, but it should/could have served as the basis for their work.

Then the Corellian trilogy posited that shields were only turned on when engines and weapons were not used, because supposedly the shields would block the emissions of those pieces of equipment if they were active at the same time. However, it was now canon that shields were a bubble surrounding the ship, not embedded within its armor.

Then by the X-Wing series shields were canonically declared both a bubble system as with the Corellian trilogy, but they would blink off for the fractions of a second necessary to allow the weaponry to fire out of them, and they were tuned such that they did not block the emissions of the engines. This allowed for the gaming-consistent representation of shields as an always-active protective bubble around the ship, and everything was nice and happy.

.....and then the source books (New Guide to Weapons and Technology specifically) said that shields were layered like an ogre onion, starting as a bubble and layering down to be a final layer within the ship's hull itself, bringing everything "in line" but still managing to contradict everything at the same time.

The EU crew also allowed Crystal Star to exist, which might be an even bigger failing.