What I did was to initially test regularly to find the levels of uptake in my tank, then maybe monthly, and now I have dialed in my nutrient dosing.
In my (understocked) 250gal tank, I change 5 gallons (2%) every day.
EI means you add a surplus of nutrients. Not that expensive, but for a 300gal tank, if you add a lot and then remove a lot, it adds up too. So some initial testing to dial in things might really be beneficial in the long run. Plus it gives you some better understanding of the dynamics in your tank.