Compact is built to save lines. Body text is 9 points instead of 10, margins are 38 points (about 13 mm) and the space between sections is cut by a third.
The biggest saving is in the job header: title, company, city and dates share one line, where the other templates use two. With six jobs, that alone recovers six lines.
Use it as a last step. Write the resume in Modern, cut what is weak, and switch to Compact only if a strong page still spills over by a few lines. The page counter above the sheet tells you when it fits.