It takes months to build a skill and only a few lazy weeks to let it rust. Keep a little oil on it.

Skills fade on a different curve than they build. Months of slow accumulation can thin out over a few unattended weeks, not because the ability vanished but because the parts that felt automatic stop being automatic. Getting it back is quicker than building it, though it never feels that way at the start.

Pick the one skill you would genuinely hate to lose. Give it fifteen minutes twice a week, even when there is nothing to prepare for. Maintenance is unglamorous and cheap, and it saves you the whole rebuild later.