I remember there was a topic in the old forum before this, about Useful Postal Informations and Stats but I can’t find if it’s already moved to this forum (correct me if I’m wrong).
In Indonesia, there are two types of post offices: normal post offices, and Agen Pos (‘postal agents’). Both are still under Pos Indonesia, but normal offices generally operate 6 days until 3pm. Meanwhile Agen Pos are managed by individuals so they are more flexible, but can differ from one another. Some open every day until evening, some have pick-up services, some sells postage stamps, some are not. Things may be different in other provinces too, so I can only share what I know around my area.
Apart from sending letters or packages, we can pay bills and transfer money at all post offices and Agen Pos (I’m not sure about collecting passports, and they are not combined with bank like in some countries). They also sells stamp duty, but not all sells postage stamps. Smaller offices and Agen Pos are usually only sell a small variety and boring postage stamps. Postcards or other mail items are only available at bigger post offices, philately shop, or online shop(s).
Pick-ups are only for packages. So you have to go to the post office directly to send postcards (unless you ask the delivery courier, and that if they are willing to help). No outgoing mail boxes in houses or on the streets . It’s possible that very few mail boxes are still exists, and even fewer are actually operating, but they are usually close to the main post office anyway so it’s easier to just hand the mails over at the counter.
In general, mails are processed manually and stamps cancelled by hand (not by machines). International mails are all sent by air whenever possible, so there’s no need to attach “Air Mail” stickers.
We have 6 days delivery (Monday-Saturday). Not everyone have mail boxes so sometimes the mail couriers just slip the postcards under the door, or in my case, stash them in a hemlet rack (it became my un-official mail box ). For packages, usually mail couriers have to hand it over to the recipient directly (or family member in the same house). But sometimes if they are already familiar with the residents they just put it near the door if nobody is home. If it’s an important item or need payment, they will bring it back to the office to be delivered the next day.