Despite the obvious benefit of chalk for climbing—its drying effect on sweaty hands—climbers can often get carried away with it. Over the years, chalk gets caked onto holds, forming layers, which affects the texture of the rock and the friction of that very poor sloper. Too many ticks can also cause confusion on a route, botch on-sight attempts, and ruin the self-discovery and problem-solving aspect of climbing.
If there is one trend I noticed during my time in Colorado it’s that you would think boulderers were going blind with the amount of tick marks being used these days. It was not uncommon to walk up to a boulder and see multiple tick marks, often garishly long, per hand and foot, with the person who actually put them there long since gone from the problem. Usually the harder the boulder, the worse this problem got.
Judicious and discrete use of tick marks for key holds that are cleaned off after every session is one thing, using tick marks like tape in the gym is something completely different.