One of the most prevalent misconceptions is that staking the castle nut isn't necessary. While many modern AR15s can function without a staked castle nut, staking it provides an added layer of security to ensure the nut doesn't back off during use.
It's not so much about personal preference. It's about what is proven to work.
When To Stake The Castle Nut On AR15
Assuming using a traditional commercial or mil spec buffer tube. Staking the castle not in at least two spots are proven to hold in the buffer tube tight on the rifle.
When done correctly, staking the castle nut should not damage or affect the buffer tube in any way. The staking process is meant to deform a small portion of the castle nut, not the threads or the buffer tube itself.
How Much To Displace The Material
The best type of castle nut to stake is the one that offer deep staking notches at almost 30 - 45 degrees. Shallow notches aren't deep enough to displace material to hold the castle super tight.
Stake with a pin punch enough into at least 2 notches, 3 taps and you're good to go.