Real Customization or Just Marketing: Are Customized Versions of Chat GPT Useful? - Eduardo C. Garrido-Merchán; José Luis Arroyo-Barrigüete; Francisco Borrás-Pala; Leandro Escobar-Torres; Carlos Martínez de Ibarreta; Jose María Ortiz-Lozano; Antonio Rua-Vieites (CoRR, 2023)