Many assumptions being made in this thread, the following quote is an example as I will explain:
The first rule of ammo testing a rifle without a tuner is, there are no rules. Do not assume one type/lot of premium ammo will show you how accurate your rifle is, there are times when Center-X, RWS R-50, Eley Tenex, etc, can perform quite poorly in a particular rifle. It does not mean the ammo is bad, nor does it necessarily mean the rifle is bad, so then, what the heck is going on? It's this thing called barrel harmonics, or vibrations, if you will, and they are absolutely critical to rimfire accuracy. The reality is that you face the prospect of possibly testing many, many, many kinds of ammo in order to find something suitable to your rifle if it is not equipped with a tuner, or you can get lucky and one of the first few things you try gives you accuracy you are happy with (happy with and "the best the rifle can do" may be two different things, however). Anything can happen, so make no assumptions.
For those worried that their rifle might only "like" something expensive, consider fitting it with a tuner instead. For the cost of a single brick of Eley Tenex (well, maybe a little more but certainly less than a lifetime of buying Tenex

), you can fit a tuner and go back to using SK ammo (or the RWS/Eley equivalents for the price point) to appease your budget while shooting 0.2's/0.3's with a high degree of consistency if your rifle is capable (most Anschütz rifles, good examples of CZ's, Savages, etc) and you've set the tuner properly. You don't strictly need the most expensive ammo to shoot 0.2's/0.3's at 50 yards, but the system has to be in tune and the ammunition at least decent!
There was a comment "faster is rarely better with .22s", I will assume the poster was thinking that "higher velocity" ammunition is only such things as Winchester value packs, Thunderbolts, Golden Bullets, Federal Blue Box, etc, and indeed such ammo is rarely associated with a high degree of accuracy. However, there is quality HV ammo being made, with RWS R-100 being an example that is more expensive than R-50, RWS Rifle Match "S", SK High Velocity, etc, and since this is quality, European made ammo, it can be quite accurate despite it's high velocity designation. Some rifles will prefer a hotter load, but it'll have to be the quality Euro stuff, not the cheap North American bulk.
How far down this rabbit hole do ya wanna go...