v, z and f, s
Hello, I've been learning dutch for quite a while, but I still have trouble in pronuntiation. I've also heard that some people neutralize the pairs v-f and z-s to just f-s, or that in some words, vijf and zes being the most recognizable, are pronounced like fijf and ses.
So my question is, how important it is to distinguish the pairs? And which dialects distinguish them?
(for context, I'm more interested in the western flemish dialects, since that's where I'll be traveling more)