I always find myself bringing Sonic to the edge of capsules like this to see his edge animations Do you have any gameplay habits like this?
In regular acts, I usually jump right before the score tally starts to gain control over Sonic, even if there's no bonus emblems to get like in Sonic 1... Which renders it useless.
In Sonic 2 and the end of Act 2's I always rev up the spindash and let it go during the fade out since it makes a cool sound (on the Genesis anyway. No idea what the hell happened to the spindash sound in say, Mega Collection).
I make Tails suffer in S3K. Prime torture hot spots include the boss area in Angel Island Act 2, and Sandopolis Act 1.
Every time I play GHZ act 3, I take the bottom route and get the extra life under the waterfall, then use the spring to reach the middle route and backtrack to get the extra life on top of the loop. In fact, I often play Sonic 1 trying to get as many lives as possible.
In Sonic 1 and 2, I always jump off screen after the sign post to regain control of Sonic and then have him look up at the score tally. In Sonic 3, I try to position Sonic next to the sign post to make him look like he's leaning against it. I also like to have Sonic balancing on the Sonic 2 Capsule.
I tend to bounce nonsensically with the bubble shield, especially while messing with the Act 1 sign. Also this, usually with the aid of the electric or bubble shields.
In Sonic 1 for the Master System, I like to jump to the right before the sign post hits the ground. This causes the camera to slowly drift towards the bottom. On the same console, I also like to try and jump over the UFO in some acts of Sonic 2. Other than that, I usually jump off loops in the Mega Drive games so I can roll off extra fast, but I'm pretty sure a lot of people do that. I also like to make the characters look in the direction of where things are happening, but I have that habit with pretty much every other game. Though it's still pretty funny to turn around and moon Knuckles as he's trying to piss you off.
I seem to like making Sonic jump in front of the capsule after hitting it, maybe to make it something like Lost World.
The beginning of Hydrocity Act 2 used to freak the balls off me when I was a kid; when I play the game now I still try to blast through that section as quickly as possible - not for scores, but because I still get fairly anxious. I still try and bounce on the miniboss that torches Angel Island Zone even though I know it doesn't do anything. I always duck and pass through the floating platforms during the little lava surf in Marble Zone.
I tend to pause and unpause Sonic 1 and 2 during the final note of the Act Clear jingle. If you've never done it, try it and take a listen :p
Sometimes while playing Sonic 2 I like to keep jumping on the capsule while the results screen is playing. I also like to spindash while the results screen is playing sometimes too. :v: And every once in a while I like pausing the game right after colliding with a spring too. xD I just think the sound effect sounds funny whenever you pause the game. xP