Dairy farmers regularly decide whether to keep or replace a cow in their herd. This replacement decision has a big impact on animal welfare, the environment, and farm income. Many people believe that cows are often removed too early, before they have reached their full productive potential. In this study, we looked at detailed records from 29 Swiss dairy farms over five years to understand how these decisions are made in real life. We used a tool that calculates the economic value of each cow based on her health, fertility, and milk production. We then compared the farmers’ decisions to what the tool suggested. We found that most farmers made good economic choices, but that some cows—especially younger ones—were removed earlier than necessary. While these early removals sometimes make sense financially, they are not ideal for the environment or for the well-being of the animals. On average, these suboptimal decisions resulted in an economic loss of 161 ± 164 CHF per farm per month and 1.55 ± 1.58 CHF per cow per month; also, economic loss from retaining unprofitable cows was about three times greater than from premature culling. This study helps explain how farmers make these decisions and shows how future improvements in health and breeding could reduce early culling and support more sustainable farming.