In the dialogues, in Spanish language text books, the characters all have names like Francisco Garcia and Maria Hernandez. It's true there are plenty of Marias and Franciscos in Spain. They are often disguised though. Many of the Marias are, for instance, Maria Luisa or Maria Dolores or Maria Mercedes so that they become Marisa, Lola or Merche whilst Francisco is Paco or Kiko. José Marias are Chemas. Hard going for the novice but not so different from the confusion that is Rob, Bob and Bobby or Chas, Charlie and Chuck. Christopher Marlowe was Kit after all - Kit Thompson anyone?
It may be true that Garcia, Gonzalez, Cueva, Rodríguez and Lopez are the most common Spanish surnames nationwide but it seems to me that nobody, whose name you want to remember, is that easy. To give a random example the authors of the present Spanish Constitution were Gabriel Cisneros, Miguel Herrero y Rodríguez de Miñón, José Pedro Pérez Llorca, Manuel Fraga, Gregorio Peces-Barba, Miguel Roca Junyent and Jordi Solé Tura. The woman who does the gossip show that Maggie watches is called Anne Igartiburu (Basque name) and the Spanish national football coach also has a Basque name, Julen Lopetegui. Other regions have local names too, so a Carlos becomes a Carles in Catalan like the honorary Belgian Carles Puigdemont. Sometimes the names themselves are straightforward enough but they are a bit on the long side. Soraya Sáenz de Santamaría is the vice president of the current conservative government and, in the last socialist government, we had a María Teresa Fernández de la Vega Sanz. Neither of them of them are exactly Antonio Garcia or Maria Carmen González. Antonio and Maria Carmen are the most common first names, at present, amongst the Spanish population and Garcia and González the most popular surnames. By the way the most chosen names for newborns at the moment are Hugo and Lucia.
In Yorkshire, when I was a lad, there were lots of Sykes, Crossleys and Thorntons and around Pinoso we have Deltells, Alberts, Domenechs, Espinosas, Ricos, Miras, Escandells, Brotons and Carbonells as well as many more. When couples marry the children get a surname that is a combination of both surnames. If John Smith married Mary Bown they could choose either Peter Smith Brown or Peter Brown Smith for their son Peter with the Smith Brown order being the more traditional. A walk around the local cemetery reveals a veritable treasure trove of Carbonell Carbonell, Brotons Brotons and Rico Miras.