aim is only a small part of getting good at cs
As an inevitable result of the frequent discussion of this topic some rather harmful misconceptions arise, such as the idea that you have to stay on one sensitivity or you will lose/significantly-damage your ability to aim.
A large part of the reason why people believe they have to keep their sensitivity the same is due to the familiarity they have with it. While playing on a given sensitivity you gain a general sense of the relationship between the motion of your mouse and your view in-game.
These aspects result in the sensitivity becoming more comfortable to use as you are never surprised by the results of your input and the extent to which you need to utilize parts of your arm.
As a result people will then tend to get scared off by changing their sensitivity as they lose the familiarity it has to them, which is compounded by having to adapt to performing various types of motions with parts of their arm they aren’t used to.
It is important to understand however that much like any other aspect of aim, you can develop and refine your ability to adapt to a new sensitivity. There is also an irrefutable wealth of anecdotal evidence within the aim training community of players changing their sensitivity constantly, even using sensitivity randomizers, all without a noticeable long term penalty to their aim.
There is even a clip where one of the best LG duelers, Serious, switches to extremely fast sensitivities (3cm for instance) and still beats Zexrow.
It is even often suggested to try changing your sensitivity to overcome plateaus in improvement as a new sensitivity can give you a fresh starting point to improve from.
Some may argue that holding an angle in the same position at the same level and tightness in tactical-shooters like Counter Strike or Valorant, may be more related to memory, but even in these instances there is plenty of variance, especially in both auditory and visual reaction time. That alone shows that sticking to the same sensitivity isn’t a strong enough factor. Sure there are benefits and downsides to using a certain sensitivity, but most of it is related to comfort .