Comprehensive information and links to required posters (all free of charge) are found at http://www.twc.state.tx.us/ui/lablaw/posters.html
Posters should be displayed in such a way that each employee can readily see them (generally, the requirements have language such as "conspicuously placed" and "readily accessible" to employees). That would mean that employees who do not normally get to certain offices would not be served by posters displayed at those offices. The offices, or sub-offices, where those employees normally congregate would need to have the posters displayed for the benefit of the employees who are served by each such location.
Posters and other kinds of required notices do not have to be placed in individual locations that are only temporary worksites. Example: construction workers building homes in a subdivision would not need to have posters in each house, but rather only in a company jobsite trailer for the project.
In case of a co-employment situation, such as temporary employees assigned to client companies, the employees working at client sites are co-employed by the staffing firms and their clients under various state and federal employment laws. The notice statutes merely require the posters to be in the workplace. The enforcing agencies do not care who actually places the notices where the employees work, as long as the posters are up and visible to the employees. Thus, as long as the client companies have the applicable notices properly posted, their compliance with the notice requirements inures to the staffing firm's benefit. By the same token, if the clients do not have the notices posted, the staffing firm would be co-liable with them for non-compliance with the laws. Bottom line: the staffing firm needs to determine whether the appropriate notices are posted in the clients' locations, and if they are not posted, cooperate with its clients to get the posters displayed.