These techniques can be very helpful for dealing with fast gravity in Sega Tetris.
It's often useful to rotate a piece 2 or 3 times in quick succession. This can help to get a piece to the desired orientation before it lands, or after it lands and before the lock delay expires. The original arcade game featured 3 rotation buttons which all rotated counter-clockwise, and the version released with the Japanese PS2 game Sega Ages 2500 Series Vol.28 Tetris Collection remains faithful to this. For fast triple rotations, pressing three separate buttons in rapid succession is far faster than repeatedly pressing a single button three times.
Rotation After Landing
When the gravity is fast you want to rotate only after the piece has landed, whenever this is possible. Here the player has an active L and an O coming next, and wants to stack them against the left wall. If the player is unable to rotate twice before the L reaches the left wall, it will get stuck in a vertical orientation. It won't rotate a 2nd time because there are no wall kicks.
It's much more reliable in this situation to wait and only rotate after the piece has landed. After it lands, release left then rotate twice. You only have to be quick enough to beat the lock delay, not the gravity or DAS.
When the gravity is fast and you have a high stack it can be extra tricky to rotate the I, because of the lack of IRS, ceiling kicks, and floor kicks. You need perfect timing in this example.
It's much more sensible here to build a platform in the center and skim while you wait for another I.
Now the I is easier to rotate, because once again you're racing the slow lock delay instead of the fast gravity.
This next situation is a little tougher than it may appear. If you start shifting too early you can miss the platform.
If you wait too long before shifting, the I may not reach the wall because the rotation doesn't cause a lock delay reset.
What you have to do is start to DAS as soon as the I lands, and then rotate while shifting.
Rotation Before Landing
This is riskier because it requires precise timing, but it has to be done sometimes. The shape of your stack can cause pieces to get stuck if you wait too long to rotate. Let's say you want to place the J rotated twice and into columns 1-3. It can get stuck in the center like this.
Shifting to the wall first doesn't help at all.
If you try to shift and rotate, you can get stuck against the wall and the piece won't kick off.
The proper technique is to rotate twice while the piece is falling, and only begin shifting after the 2nd rotation.
Because only counter-clockwise rotation exists in Sega Tetris, and because of the lack of wall kicks, the number of available twists is limited. The only ones that work in mirrored situations are S and Z twists.
These twists can only work as shown below (no mirrors).
The fast DAS in Sega Tetris allows for moves that aren't possible in most other games with fast gravity. Here the T can jump over the open column and stack nicely against the wall. When left is pressed and held, the piece first moves one column left, pauses, and then the auto-shift takes over. In this example you wouldn't want to shift and rotate as the piece is falling because it could easily get stuck against the left wall after one rotation.