How fast should a speedster be to be considered useful?

Not every speedster is as fast as the flash, classic marvel speedster The Whizzer was said to run only 100 mph in his prime. It had me thinkin, what minimal speed is considered good and useful for a speedster?

I will stick to the low end for the moment and not count people who are far beyond Mach speeds or hypersonic

Here are Three Types. A few types to consider, the low end speed blitzer, the aim dodger, at times they might seem only like a peak human athlete, peak martial artist but they are more they are aim dodgers. Type 1 Take Batman types Black Widow, Daredevil types etc its seems they almost dodge bullets but the don't really, incredible senses and skills allow them to aim dodge, it is like dodging a thrown ball or a snow ball, it does not mean you move as fast as the ball but they are still incredibly fast that is fast enough to doge where the person is aiming the gun. Batman and Daredevil are pretty close on skills, as good as Batman seems he might only be the 5th best martial artist in DC, he could be as low as 10th there are at least 4 faster, more skilled and better than Batman.

2nd Type 2, the guys who have some mystic precog kungfu mental mutation power, they can predict where everything is going to happen which makes them even more dangerous than an aim dodger, take some of the mystical DC martial artists or guys like Spider-Man on an ordinary day. The Mandarin is a strange one he's a powerful Ironman enemy with alien rings, he shows off a lot with hand to hand but has few speed feats to put him on this speed level, the reason he tends to do so well in battles is he amped his 'chi' to level where he's basically as tough as The Thing from Fan4, the Mandarian can laugh off attack from an enraged Ironman. Others use their chi or mystic power to amp their speed or reflexes top close to bullet time might be Lady Shiva, Deadpool, Deathstroke, Richard Dragon Bronze Tiger depending on debate over PIS feats or not, PIS being Plot Induced Stupidity ..Spidey maybe not faster than a bullet but almost as fast, quick enough to dodge multiple gun fire, the mystic batgirl Cassandra Cain may be bullet time not sure, Spidey also could be bullet time or beyond, feats start to go a little weird at this speed and there is always a debate about what is historically accepted and 'canon'

3rd type genuine bullet time and beyond Mach speed, movie Quicksilver in the Avengers would fit here, Joss had said he was faster than a bullet, the original Golden Age Superman was also fast or faster than a speeding bullet. There's debate as to whether many DC, Marvel or Image characters are truly bullet time if or not she or he's a bullet-timer, is their own natural speed faster than a bullet or are they using powers of precognition is at least partly to answer for their feats, but at this speed does it really matter. A true bullet timer will basically dodge bullets AFTER they have been fired.

that's my take on it

Once they hit around supersonic it start to be another level.

I’d say a speedster should at least be FTE

Supersonic.

Faster than a speeding bullet.

Depends on your universe

If they're faster than at least most of their opponents. That's all that really matters at the end of the day.

Any level of speedster would be useful just needs complementary skills.

Captain America/Black Panther speeds (60-80mph+) would be a useful level of speed even more so if (unlike cap/BP) this is just their jog speed not sprint speed. Once you get in the hundreds you are talking incredible speeds like just imagine going 80mph on the interstate and seeing a person fly by at say 200mph. It would be insane much less 500mph.

Once you get into speeds high enough to outrun bullets you are talking potentially 3000fps+ (at least 1500fps). At ~3200fps you would be as fast as the fastest air breathing manned aircraft in the world (SR-71).

If you want to leave bullets in the dust then you are talking up around Mach 10 (~7,700mph) which would put you over 2X the muzzle velocity of most rounds and faster than the speed of the experimental unmanned hypersonic scramjet the X-43A (7,307mph).

To really make a joke of bullets jump up to 20,000mph. You are now exceeding the speed of a space shuttle launching into space and over 6X the speed of most bullets.

Now to shorten the numerous steps I could take working my way up I’ll just end on this at 1% of the speed of light you are at ~6.7 million mph at this speed you are going ~1860 miles per second you could travel the circumference of the earth in ~14 seconds (ignoring obstacle, just in terms of distance) or for a completely unrealistic example if a sniper took a 1000yd (3000ft) shot and the bullet traveled 3000fps the entire way to its target you could be in San Antonio, Texas and the shot being taken in NYC and if you left at the same time the trigger was pulled you could have moved the target over 30miles away before the bullet got there (assuming you used a car route to get there + ignoring traffic + instant acceleration....etc.). The distance you could go in a blink of an eye (1/10 of a second) would be 186 miles approximately.

It is due to the mathematical reality of things like that last one that is why it is ridiculous that anyone who isn’t also at speedster levels could hit a “light speed capable” Flash not to mention how ridiculous that anyone who didn’t have significant durability could stand up to punches with that much energy behind them just consider how light a bullet is compared to a fist and it is moving considerably slower than Flash’s fist. In reality it would take major restraint not to kill anybody and collateral damage would be significant idek what would happen to the surfaces you ran on.