Maybe things Just Work so long as you avoid hiring jerks, and people feel secure enough in their jobs that they don't see the need to anxiously compete with their teammates. (Some company cultures definitely go the opposite direction, favoring cold-blooded ambition over prosocial cooperation.)
If there are regular weekly kudos, it'd be a team-specific thing.
/++ were really common before a couple of years ago, but I get the vague feeling it's usage is declining. It used to report the accumulated number of pluses you got... So you could tell who have been the really helpful folks (or really tenured folks) out there, and for great contributions, you'd really want to chime in to a wave of ++s to show your appreciation.
Without the numbers, usage seems to have declined a bit, since there isn't the satisfaction of seeing a colleague's karma go up by, say, 10pts after a great presentation.
Still, it's a great culture tool, and something I'd want to spread at my next employer's if I leave the company.
We have all probably experienced working really hard on something that isn't very visible and receiving very little credit for. We have also probably experienced working on a flashy but relatively simple feature and getting lots of praise for it.
It would be a good way to quantify small things like answering questions, giving good code reviews, etc. that can go unnoticed.
Honest question if your team also does this. How do you differentiate real thanks from the thanks of the week? I ask because in my experience kudos at a regular interval works for a while when it is launched but stops being effective over time, in some cases producing the opposite of intended effect.