Coco holes less water / more air than soil, so it would have that impact.
Perlite or hydroton may be better for what you want? Either way, you'll have to water slightly more depending on the proportion of coco or anything else added with tose properties.
Coco can become compacted like soil, so add something like perlite or hydroton to create air gapes and improve drainage which also helps avoid compacting substrate a bit as you water over 3+ months.