Complex sentence: These began at a rate of one volume every six months, however, as the cinematic release of Luc Besson's film "Valerian and the City of a Thousand Planets" approached, the rate increased to one every three months.
Split into simpler sentences: These began at a rate of one volume every six months. However, as the cinematic release of Luc Besson's film "Valerian and the City of a Thousand Planets" approached, the rate increased to one every three months.