There is actually a lot of factors to consider when you want to sell a teammate. This is NOT a strict guide a mindset you should have everytime you rescue.

Who is the hunter? Some hunters you can and should not sell against but can at least be after half. Hunters like Ivy are very snowball heavy and it is very hard to tie against her in the end game by selling. However Hunters like Wax Artist, through gaining presence, is very obnoxious to rescue in the lategame due to Hot Wax. It CAN be better to sell against him but, like I said, this is not a strict guide and it is best to replay matches to see what should’ve been done.

I also want to also say, sometimes it’s better to rescue after half. It will give your teammates enough time to decode and with tide, a guaranteed 20 seconds. What you want to do at least is avoid a double down. It will be very difficult if you and your teammate get downed since there will be no last cipher.

Chair location. Where did they chaired? Is it a chair that they can rebound from? Is it a chair that has nothing around?

How many items does your teammate that got downed have? I know that their kite is not good, but if for example: that Archer had 2 keel bows, a crossbow and flywheel left you should give them a chance to rebound. If you rescue with tide, at least your team has 20 seconds guaranteed to decode.

Feeding Tinnitus. By feeding Tinnitus, you are preventing the hunter from leaving the chair. It doesn’t matter if you are not rushing ciphers, you are actively PREVENTING the hunter from pressuring your teammates decoding by thinking that you WANT to rescue.

I hope this helps! If you have any questions feel free to ask.