I only occasionally place healing potions in encounter areas as treasure, although a mid-level NPC or a bandit captain might have one or two on them. However, most towns in my setting have a temple, alchemist, or herbseller who sells them, and almost every city will have multiple opportunities to purchase them, including the stronger versions. Thus I leave it up to the players to determine whether they want to have them, just in case. I will also sometimes give them out as quest rewards, for example if the party is going on a mission to help out a local temple. I once had a quest where an adult copper dragon offered the adventurers a cache of six potions of superior healing in exchange for assistance; those potions are rare and expensive enough that they feel significant when found.