Organic soil may decompose quickly and turn to sludge. Sand can be an excellent ingredient but also one of the worst depending on the granulometry. For example fine sand used in construction is maybe the worst ingredient, but even this I found out that it is even worse when mixed with organic soil instead with clay. Some plants produce quickly an extended root system and soil composition is less important, because pot is filled fast with roots. But other palms produce rather only a deep wire like root, because in habitat surface soil is very dry and therefore root has to tap deeper and moister layers. Latter plants suffer enormously through muddy substrate. To get an idea, my Leucothrinax seedlings stayed all in a high liner ( serving as community pot) filled only with perlite for two years after germination, before being individually potted up. And even then substrate consisted of 80% very porous materials like zeolite, oyster shells and perlite.
