Duna: Is it always more efficient to aerocapture than to do a capture burn?

I know this sounds like a dumb question, but hear me out.

Capture burns are obviously extremely expensive because the spacecraft needs to carry a bunch of fuel with it all the way to Duna. However, heat shields are also pretty massive. For larger spacecraft (e.g. a return mission), with large or extra-large engines, and especially with detachable boosters, I'm wondering if the mass of the heat shields might sometimes weigh more than the fuel that would otherwise be required to do a capture burn. My understanding is that heat shields are not required on Duna from low orbit based on the following readings:

This SE question

This discussion on the KSP forum

But presumably heat shields are important when entering the atmosphere during hyperbolic orbit (right?).

Are there ever situations (given spacecraft mass, descent profile, transfer speed, etc) where having heat shields results in a more massive spacecraft than just doing a capture burn? Regarding this issue, what are the best practices when designing a spacecraft?

The reason I'm asking is because I'm building a mission planning tool and I don't want to make a blanket assumption that heat shields are always the way to go.