worthwhile or a waste of time practices.

[GrantA]

Brass is lc..or sorted by headstamp commercial.
I do have some new lapua and new lc brass as well as new federal

If you want tiny groups consistently without neck turning stick to the lapua, I can't comment on LC neck wall variations, perhaps someone else can?

Have rcbs prep center so flash hole deburring would not be tedious..I don't do it at this time though.
I do have hornady primer pocket uniformers that could be run in prep center..

I became a believer in flash hole deburring when I kept chasing big velocity spreads working up a subsonic 223 load. deburring flash holes got them tightened up, primer can ignite evenly. You'll be amazed at the shavings after doing it and it's a one-time thing.

I Don't turn necks at this time but have seen k&m as well as 21st century turning tools..
looks like a PIA, but with a power screwdriver still doable, if it provides meaningful results.

tell me when you're going to do it, I'll drink an extra beer or 3 for ya

I Don't have a concentricity guage but the neco would be on the short list for what it does. Followed by sinclair

neco gets great reviews, so does Hornady actually

Standard dies and brass work for me so I haven't had to turn necks due to tight chambers

I have'nt annealled yet but have seen some info on using the tempalac and a rotating socket, or in time to a metronome..
I suspect I will have to do this more for the brass that is hard(er) to find than common calibers and I have less of it as well as it is being pushed harder, but it will still apply to other calibers.

When do you anneal is it every x number of firings, or dependendent on how hard you push them.

If you're going for tiny groups anneal every time, it's not about brass life as much as it's about consistent neck tension. I have been meaning to work on an annealing setup but have too many other projects going on, plenty of videos on it, have fun!