To a first approximation modern li-ion batteries don't really care if they drain 100->50 once or 100->90 five times: the wear on the battery is more or less equal. Exposing your batteries to extreme temperatures (below freezing, above 40C) or allowing them to self discharge below the safe low voltage limit has a far greater impact on overall longevity.
"The shorter the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses"
Keeping the battery constantly at stable 60-80% charge is far better than doing full discharges every month.