It is an effort to produce consistency.
Like selecting a batch that suits your barrel and even a specific die.
Lead content Vs antimony content.
Some pellets can have lots of swarf. Others covered in graphite and other crap.
Head size uniformity is important and many will use a sizer although imho, unless its a damned good one, your more likely to damage than fix. Skirt size is less important as I see it... its gonna have 180 bar plus going up its chufter.....
Do not use dish soap. Contains salts.....
Weight can vary a lot so weighing isnt bad.
Generally, a good regime will get to that extra point or so in a comp.
Is it worth it... personal shout. I used to do some of these things. I dont bother now.
In a battle of wits I refuse to engage with an unarmed person.
To one shot one kill, you need to seek the S. Kill only comes from Skill