Default utility lines are often mistaken for static coordinates, but grenade trajectories depend on initial velocity, gravity, collision normals, and bounce decay. Version updates shift the mid-flight reference points and tolerance bands, so re-learning utility is about recalibrating what you look at, not where you stand.
Default utility lines are most easily misunderstood as a set of static coordinates: stand here, aim at this corner, jumpthrow, and the smoke lands there. Learn it once, write it in your notes, and copy it every patch. The problem is that a grenade's path from release to landing is not a straight line but a trajectory determined by initial velocity, gravity, collision surface normals, and bounce decay. When a patch drops, what breaks first is often not the "spot" but your memory of the middle segment of the trajectory.
Look at the trajectory in three segments, not just the landing point
I break a grenade down into three segments: release, flight, and collision. Release determines initial velocity and angle; flight determines whether it gets eaten by mid-air geometry; collision determines the final landing point after bounces. Most people only remember the landing point, so when a smoke is off by half a meter, they blame "shaky hands." But the real cause is often the collision segment: the texture on the same wall hasn't changed, but the seams of the collision mesh, the height detection of boxes, or the slope of a roof gets realigned in some update. Your release was fine; the transition between the second and third segments changed.
That's why default utility lines need to be re-practiced per version. What you re-practice is not "where to stand" but "where to look." You need to reconfirm the reference points the grenade passes through mid-flight: which edge of the eave, which pixel of the box corner, which color band of the skybox. The landing point is the result; the reference points are the reproducible input.
Bounce is hidden depreciation, not a fixed tax
The trickiest thing about bounces is that they look stable. A flash that bounces off a wall lands in the same spot twenty times, then on the twenty-first it suddenly hugs the ground and rolls into a corner. You think it's luck, but actually the incident angle has approached a critical value: a slight difference in angle and the normal component sends the velocity in a completely different direction. If an update adjusts the orientation or friction parameters of any collision surface, this critical line shifts as a whole.
So when I practice bounce utility, I deliberately record a "tolerance band": how many degrees left or right still works, how many steps forward or back still blocks. Utility with a narrow tolerance band depreciates fastest in essence, because a slight version change knocks it out of the window. In default utility lines, prioritize the ones with wide tolerance bands and treat narrow-tolerance ones as on-the-fly patches, not tactical backbone.
The re-practice ledger: three lines, one pass
My re-practice routine is crude but saves time. The first line is the "verification line": throw only the five most-used default smokes, record the deviation between landing point and reference objects, and judge whether it's a global shift or a single-point drift. The second line is the "bounce line": pick two bounce-dependent grenades and test whether the tolerance band has narrowed. The third line is the "alternative line": prepare a flat-throw version that doesn't rely on bounces for each narrow-tolerance grenade; even if it doesn't block perfectly, it can cover you in the first twenty seconds of a round.
The point of this ledger is not perfection but turning "it doesn't work this week" from an emotion into a locatable problem. Grenade trajectories depreciate with versions, and so do default utility lines. What's truly stable is not a particular smoke but your method of recalibrating it.