How much tactic training should you do per day?

At least 15 hours.

Setting sleep to 8 hours. That's 30 minutes left for watching a nerdy movie, 29 minutes to order a pizza and eat it, and there's a minute left for personal hygiene and care, which is even maybe too much for a chess player. If you cut your hygiene down you can do tactics for 15 hours and 30 seconds.

The 30 seconds may not seem like much, but over the 20 years of training needed it adds up, and may just get you that advantage in pawn structure than makes you win. So my advice it mainly to learn to cut personal hygiene.

Now you're just trying to hurt my feelings sir....Wait, how did you learn about my new TT approach? 

I actually have a new personal regimen that is based on the V3 theme training AND reviewing failed problems.  I'm doing 10 from each theme and I'm doing as many themes as I can and then rotating right through until; wait for it,  I've learned from my mistakes. 

It is obviously depended on your level. You can see here if you need to train tactics

I like watching the patterns everyone should know video series - the one on tactics and the one on mates.  Then following up with some tactics trainer...

everyday i do 10 very easy ones on chesstempo and then do the 5 i am allowed to do here which are harder, no point in doing more than that until i plateau

40 to 60 mins per day is fine, I guess. if you are getting bored, or tired, then by all means stop- chess is mainly fun, and should stay like that for an amateur.

Needless to say, that study is not worth much if it does not translate to "something" OTB. A good study program cannot be laid out in general- should be specific to the player.

There is only 24 hours in one day!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

I do 5 tactics. That's how many chess.com allows me to do. It's probably because they think I am progressing really fast and don't need anymore than that. 

Magnus Carlsen does tactics training. 

4 tactics puzzles a day as a warm-up is enough

You should limit yourself to five positions per week, but learn each one thoroughly.

(I’m throwing this out for discussion without experience implementing it.)

See 300 Most Important Tactical Chess Positions by Thomas Engqvist.

i'm solving 100-200 a day for the 'puzzle addict' achievement, but spread through the day & mostly in the early morning or late at night.

all day, every day.    😆

there aren't 30 hours in a day 

Why doesn't it bother anyone that training for more than 24 hours a day isn't possible?

Tactics training is not important. Four tactics puzzles are a good warm-up.
In a real game nobody tells you there is a tactic, or for which side.
Analysing lost games and study of grandmaster games is more important.
Kramnik worked 10 h/day, 7 days/week and studied 10,000 games per month.

Play 10 min of tactics after a game.