What to actually track (and what most bettors are missing)

You cannot improve what you cannot measure. The minimum viable betting log takes two minutes per bet.

The minimum viable bet log: date, sport, bet type (spread / moneyline / total), odds, stake, result, and closing odds if you can find them. That is six fields. At two bets a day, filling this in takes under five minutes. Everything else useful -- ROI by sport, ROI by bet type, timing patterns, edge vs. market -- is derived from these six fields over time.