Emblem templates are highly recommended for multi-piece single layer designs. If the pieces are large and there's only two or three of them you could probably eyeball the installation and get close enough.
In the example below there are two emblems, both made up of eight individual pieces. The design is mirrored so a slight misalignment would be easily noticed. Although the designs are the same, they are different sizes, therefore two templates are called for.
The template is shown below on the left and the emblem is on the right. The black chrome acrylic we used for the emblem looks cloudy and scratched due to the protective layer that will be removed after installation.
The template is simply held in place with masking tape. Start with the largest emblem pieces and install one at a time. Peel the backing away to expose the 3M adhesive. Gently slot the emblem piece into the corresponding spot in the template. Once all the pieces are installed, press firmly for 60 seconds to set. Peel the protective layer off the emblem then remove the template. You will be rewarded with a perfectly aligned emblem.
Here is another example of an emblem with individually cut letters that also needs an alignment template for install.