When we should customize Bootstrap

When Bootstrap is used with a precompiled style sheet, it has all the default colors, typography, spacing, and more that people associate with Bootstrap. When using these styles for your own project, it will inevitably look like Bootstrap unless you change these styles. This might not be a problem if you are creating a personal project or one for internal use. But if you have specific brand guidelines that your customers or users recognize you by, you will likely need to change these styles to match the style of your brand. Since Bootstrap is so immensely popular and widespread across the internet, some people might recognize the default Bootstrap styles unless you change them. That might have a bad impact on user experience, so for professional use cases, it is highly recommended to customize the default Bootstrap styles.