In Spanish it was also inconsistent in the past, in what we call pre-normative times.

The Spanish language only became truly standardised in the 19th century, when the Real Academia Española gained some reputation and started producing some top quality dictionaries, despite the institution having been founded in the early 18th century and being modelled after the Académie Française, that had been active since the times of Cardinal Richelieu.

There had been some grammars and dictionaires printed and circulated in pre-normative times, most notably the Gramática by Elio Antonio de Nebrija, the Gramática Castellana by Cristóbal de Villalón, and the Gramática printed in Leuven by Bartholomaeus Gravius of unknown author. As for the dictionaires, there were two created by Alfonso de Palencia (a Latin-Spanish and a Spanish-Latin one), one by Nebrija, and in the 17th century we have the Thesoro de la Lengua Castellana o Española, by Covarrubias who was the son of the great paremiologist Sebastián de Horozco.

The controversies on the matter of how to properly write the Spanish language lasted for centuries, with the most notable disruption happening in the 17th century. In that time we find the great lexicographer and paremiologist Gonzalo Korreas, who defended a sinplified orthography, in which all "b" sounds being written as "b" (so, "biento" and "bentana" instead of "viento" and "ventana"), and all "k" sounds written down with a "k" (Korreas, Kijote, mákina, instead of Correas, Quijote, or máquina). Korreas' ideas did not last much, but they are quite significant nonetheless.

As an example of the inconsistencies one may find in pre-normative times, I will add a text from Gonzalo Fernández de Oviedo (1478-1557), in which he uses various spellings of the same word:

muy acostumbrada cosa en nuestra España, entre caualleros e señores, procurar que la invençión comiençe su nombre en la primera letra del nombre de la señora por quien se inuençiona, demás del atributo o sinificaçión que quieren magnifestar o publicar con esas devisas. E guardando esta orden, el Cathólico Rey Don Fernando trahía un yugo, porque la primera letra es Y, por Ysabel; y la Reyna Cathólica trahía por diuisa las frechas, que la primera letra es F, por Fernando

Here we can see the indistinct usage of "divisa", "diuisa", and "devisa" within a single paragrah, when the current (normative) spelling would be "divisa".

These variations in orthographic manners stem not only within a same author, but across authors, and they emerge mostly from different dialectal varieties in the Iberian Peninsula. This can be quite well seen in Cristóbal de Villalón's grammar, which I will translate in a moment:

La X, en el castellano tiene la mesma pronunçiaçion en el vocablo que tiene la j, larga, que el Latino llama consonante: porque poca diferençia haze dezir jarro o xarro, jornada o xornada, porque todo se halla escripto en el castellano. Verdad es que algo más áspera se pronuncia la x que la j consonante. Y por esta causa digo que se deue aconsejar el cuerdo escriptor sus orejas para bien escreuir: porque el sonido de la pronunçiaçion le enseñara con qué letra deua escreuir. Dirá jarro y no xarro. Dirá xara y no jara. Dirá xabón y no jabón. Y ansí en los demás que se le ofreçieren.

Translation: The X, in castilian, has the same pronunciation as the j, long, that the Latin calls consonant: for small is the difference in saying xarro or jarro, for all can be found written in castilian. Truth is that the x is pronounced somewhat harder than the consonannt j. And for this cause shall the sound writer train his ears in order to write well, for the sound of the pronunciation will teach him which letter shal he write down. He will say jarro, not xarro. Shall he say xara, not jara. Shall he say xabón and not jabón. And so on for the rest of the cases that come to him.