Receiving data is best using only one of the sidebands of the AM signal. This can be done by using a narrow AM filter (normal is 6 to 9 kHz, use 3 to 4 kHz instead) and tuning to the carrier and one of the side bands. Alternatively you can use USB or LSB.

Receiving both sidebands can be a problem if propagation distorts both sidebands differently, which is often the case. Using only one sideband prevents this, giving a better reception.

Using a synchronised AM detector for digital signals most often isn’t an improvement, because both sidebands are used then too.

Synchronised AM can improve music quality though. With very deep QSB often the carrier dissapears partly or competely. This can cause distortion similar to receiving SSB on an AM receiver, which can be quite catastrophic for your music experience.

A synchronised AM detector introduces it’s own carrier, which always has the appropriate level, keeping it in sync with the original carrier, even if it dissapears for a short while, hence improving audio quality very much during those instances.