Net worth (assets minus liabilities) is the most useful single financial metric. Monthly fluctuations are noise from market movements. Annual is too infrequent for meaningful trend recognition. Quarterly tracking hits the sweet spot.
How to track
Spreadsheet with sections: cash, investments, pension, property, liabilities. Total once per quarter. Compare to previous quarter and year-ago. Apps (Plum, Snoop, Beanstalk) can automate.
Most users who start tracking find their savings rate increases unconsciously. The act of looking changes behaviour. 30 minutes quarterly produces measurable financial improvement over years.