There are some special strategies for games where the time is limited, but they may be perceived as annoying/offensive by your opponent. Here's a couple of them, in increasing order of offensiveness (my personal opinion -- Morten):
As a side note, it is often said that to improve at Go, a beginner should lose his first 20 games as quickly as possible. Therefore, it may be very good for beginners to play faster than they normally do. They are likely to make lots of mistakes anyway, may as well make them in blitz, learn from them and get on with it.
-- Morten Pahle
TakeNGive: Just curious; what's offensive about unwarranted tenukis? You should be able to punish moves like that.
Fhayashi: Probably because the response to the tenuki move isn't tenuki. I think it boils down to an unnecessary change in the order of stones played in order to cause confusion.
lavalyn: One of the most confusing things to do against unwarranted tenuki is to stay where you were before. It's not *really* alive yet, now is it?
TDerz: I can only guess whether these strategies are meant to "win" games. This focusing on winning (by allegedly disturbing the partner) would distract (me) simply from concentrating on playing good moves. I do not fully understand the term "unwarranted" tenuki. If the playing partner plays consistently, hence consequently where you left, this would create a tenuki to your last move, too. It just boils down to have the better overview and play the better moves (locally, globally). I myself would not subscribe any of the mentioned ways (negative tenor) to play Blitz games (10-15 minutes). The exception would be twofold: a) the "suboptimal moves" might, in fact, objectively be the better moves, due to more aji and b) with an opponent/partner having only a few seconds left on the clock, everything you play is legitimate (this is, e.g. even explicitely stated in point 16 of the BGA Go Lightning Tournament Rules).
It all sounds as if you were giving a 9-stone handicap game, have full control over the game and are invading huge spheres of influence ("Play unreasonable cuts, invasions"). It might take time to find and create complex ko situations, but very little time to reply. Usually one plays on even however, the partner knowing as much from the game as you do yourself.
I can, however understand your intention, because I played - unintentionally - this style in 7 minute games. The reason then is simply that one or even two players lose oversight (completely or partially). It's fun for both but not optimal.
Masaaku: I find that in blitz, your strength can vary a lot depending on the person. A person who is good at blitz does not gain any skill when playing blitz, but goes down less than other players. A player who is bad goes down more. A good blitz player might lose 2 or 3 stones of strength, while a bad blitz player will lose 6 or more stones. This makes average blitz strength about a 4 stone loss. Or so I believe. It would be interesting to give a blitz game as handi, and see how it plays out.
Tapir: I recently discovered blitz games to be both fun and a great practice to learn both time control (until recently i lost quite a lot of games by time) and being less obsessed with rank.
Tapir: I recognize that quite a lot of players at my level don't read - or can't read (simple though a little long) ladders in 10 or 12s blitz games. If you do, you may start a ladder... the first two or three moves playing out the ladder should be enough to win the game. (Happens regularly on KGS at least.)