on a good tube, I still shoot a couple and clean, and build up the group size a bit. Its generally when I'm already starting to test ammo anyway so no big deal.
IMHO the barrels I've "broken in" have fouled less than those not. It really doesn't take that much extra time either.
That said on the 257 wtby factory gun, I never had time, didn't have time to DBC either, its been zero'd and shot and that means maybe 40 rounds total over the years, and never cleaned.... so far so good, hovering at moa or so...
DBC I can't find hurting any tube but like John says, it may not be needed in some, though I tend to eventually put it in for nothing else RE corrosion help...
