It occurred to me yesterday morning that I'm used to spending several hours a day alone (not every day, but most days), whereas when I'm traveling and visiting friends (or at a con, or in other multi-day social situations), that rarely happens.
So far I'm doing pretty well this trip; haven't felt a strong need for a lot of downtime, and got much of a day of downtime last Thursday anyway. But I should consider explicitly scheduling occasional time-alone during trips.
(The general idea isn't new to me; I've been thinking for years in terms of social time vs downtime. But I hadn't previously thought of it explicitly in terms of the amount of time alone that I'm used to getting daily, vs the amount that I tend to get while traveling.)