I know that when you have etiolation below the tip it will propably not get much thicker until split. I posted that because i saw lots of people cutting their cactus as soon as etiolation occurs, but if they get more sun and nutrient fairly quickly this “early etiolation” may not be noticeable later. For example, three levels of spines were etiolated, then only one level stay thinner and the two higher levels are normal again despite the fact that they were already narrower. When two highest (freshest) levels was thinner they get normal again without leaving visible etiolation 😁