You tend to give it more throttle at the start than on a conventional bike - you dump the clutch and it goes from 0-60 in 2.5 seconds, so they're quick. It's crucial to get out of corners fast in speedway, and to do this you often need to back off the throttle to control wheelspin, rather than giving it full gas.
The nature of the tracks means there's more dirt and grip in some places, so you use the throttle to adjust to the surface. You give it more throttle on grippier parts of the track, so you head for the rut, back the throttle off and give it a handful as soon as you hit the grip.
Speedway bikes have big flywheels that produce a lot of inertia and momentum, so when you hit dirt on track you really feel it. And if you hit the dirt with too much throttle the bike takes off on you. The more gas you give it the more the rear spins, but actually going into the corner it's not about engine power getting you sliding, it's about momentum and the way the bikes are built with very little weight and the weight very low. They tend to slide out and the rest is throttle control.
To stop the bike, you shut the throttle and the engine does the braking. But if you need to stop the bike in a hurry, say if a rider falls off in front of you, you have to do a controlled crash - you go into an overslide and slide off the bike. Whether you're holding or increasing a slide, everything is done off the throttle.
Throttle control must be second nature in speedway. In trials you can focus on it more because you're up against yourself, but with disciplines such as speedway, the competitive spirit comes out as soon as you get a few others beside you. If throttle control doesn't come naturally, you end up throwing everything you've learned out of the window because you just want to gas it to beat the other guys.
I've been riding off-road since I was six and made a natural progression into speedway from grasstrack. I started professionally when I was 16. That was about 17 years ago and I've been doing it ever since.