Do I need to perform my next hack within 24 hours of the current one in order to keep Sojourner alive? [duplicate]

Kei Kawai, a Niantic Labs Product Management Director, recently gave an interview (translated into English here) in which he said:

Q: Sojourner isn’t counted once every 24 hours?

A: No, it isn’t. There were people who felt it would be a shame to cut off the counter at exactly 24 hours, so we left a bit of wiggle room. I cannot give you the details, but it is definitely not counted in periods of 24 hours. You do have a little room to play with. (Actually it is quite a lot… I can’t say a little).

This strongly supports HenricF's answer.

(Aside: the interview also debunks a whole load of myths about Ingress and gives the first explanation of stickiness of portal mods that I've seen. It's definitely worth a read if you're an Ingress player).

Yes, that's the official description.

Greetings Agents, there have been some questions on how the Sojourner medal works, so we decided to create a quick overview:

• The medal tracks the longest streak of consecutive 24 hour periods in which you have hacked a Portal.

• To keep this streak active, you must hack at least one Portal every 24 hours. If you hack at 10:00 AM one day, then you’ll need to do a hack by 10:00 AM the next day to keep the streak alive.

• The 24 hour counter starts over every time you hack a Portal. If you hack at 10:00 AM, then again at 3:00 PM, you have until 3:00 PM the following day to hack again.

• You may hack any Portal - it does not have to be the same Portal every time.

• The stat shown as 'Consecutive Days Hacking' reflects your longest streak, not necessarily your current count (unless they are the same).

Though... I have no proof of it but I am quite sure that I extended the allowed time frame on one single day by some minutes and did not loos the streak.