It is not necessary to apply for trademark registration in all categories, but it is recommended to choose based on the actual situation. Trademark classification is based on the characteristics of products or services. Different classifications will have different scopes of trademark protection. Therefore, if a company's products or services involve multiple categories, it is recommended to apply for trademarks in different categories one by one to ensure that the scope of trademark protection is more comprehensive and effective.

In addition, applying for trademarks in all categories also requires consideration of the corresponding time and cost issues. Trademark applications require a certain fee, and applying for all categories will increase the application fee. At the same time, applying for trademarks in all categories will also increase the time for trademark application and review, and extend the trademark registration cycle.

Therefore, when applying for a trademark, you need to make a choice based on the actual situation, weigh the cost of time and expense, and choose the trademark application plan that best suits you.