If I am working on a long document with full justification I usully make at least one Tight variant and at least one Loose variant of my body copy styles. This is primarily to allow me to add or remove a line as needed for length or appearance.
Full justification works by taking the space that would appear at the end of the line (if using left justified text) and distributing it evenly across the line. This can be dome by adding all the extra space between each word, by adding all the extra space between each character, or by streching the characters using horizontal scaling, or some combination of the three.
Remember there are three attributes you can play with. It looks like you are unhappy with lots of word spacing, so try making the maximum word spacing lower and adding more character spacing. You can also add horizontal scaling. 1% up or down will not be noticeable and it adds one more way to adjust spacing.
In the top image I used InDesign’s default spacing, which only allows for changes to word spacing. In the bottom image I reduced the range for word spacing and added a bit for character spacing and horizontal justification. As it turns out each line breaks in the same place, but the way the space is distributed is different.
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