Guided zygomatic implant placement was superior than free-hand zygomatic implant placement, according to a recent study published in the Journal of Dentistry.

Dental implant surgery is a procedure that replaces tooth roots with metal, screwlike posts and replaces damaged or missing teeth with artificial teeth that look and function much like real ones
The aim of this human cadaver study was to compare the accuracy of guided versus free-hand zygomatic implant placement. For the guided implant placement laser sintered titanium templates were used.

Forty zygomatic implants were placed in ten cadavers heads. For each case two implants were inserted using the guided protocol (Ezgoma guide, Noris Medical, Israel) and the related surgical kit and the other two by using a free hand approach. Post-operative computed tomography (CT) scans were carried out to assess the deviations between planned and inserted implants. The accuracy was measured by overlaying the post-operative CT scan (with the final position of the achieved implants) with the pre-operative CT scan (with the planned implants).
The Results of the study are:
The difference of the mean between planned and placed zygomatic implants by using surgical guides or free hand were statistically significant for all the variables evaluated: angular deviation (1.19°±0.40° and 4.92°±1.71°, p<0.001), linear distance deviation at coronal point (0.88 mm±0.33 mm and 2.04 mm±0.56 mm, p<0.001), at apical point (0.79 mm±0.23 mm and 3.23 mm±1.43 mm, p<0.001) and at apical depth (0.35 mm±0.25 mm and 1.02 mm±0.61 mm, p<0.001).
Thus, the researchers concluded that the proposed guided surgery system exhibited a higher accuracy for all the investigated variables, when compared to the free hand technique.
Reference:
A study named, A novel guided zygomatic implant surgery system compared to free hand: A human cadaver study on accuracy by E.Grecch et al. published in the Journal of Dentistry.
https://www.sciencedirect.com/science/article/pii/S030057122100364X