Natural Dutch speech is not a sequence of isolated words — sounds blend, merge, and change at word boundaries. Linking (sandhi): when a word ending in a consonant is followed by a word beginning with a vowel, the consonant links to the next word. Ik eet (I eat) is pronounced as one unit: ik-eet, not ik (pause) eet. Het is (it is) sounds like het-is. Liep hij (did he walk) sounds like liej-hij with the p disappearing into the following consonant.
Elision (weglating): sounds that are present in careful speech disappear in fast speech. The t in niet (not) is often dropped before a consonant: niet goed becomes nie-goed in casual speech. The schwa + n in plural -en is often reduced to just n: huizen sounds like huize, with only a trace of n remaining. Dat is sounds like das (the t assimilates and the vowel weakens). These reductions are normal in casual spoken Dutch — not sloppy speech.
Assimilation: sounds change to become more like adjacent sounds. The nb in een beer becomes em beer (labial n assimilates to the labial b). The d in goedendag becomes like a d-n sequence: goeden-dag is often goeiendag or even goeiedag. Understanding assimilation helps you decode fast speech — the sound you hear may not match the written form. For production, aim for natural connected speech after reaching B1 — before that, clear articulation is more important than linking.