In most CO2 enriched tanks with moderate to high light, dosing 2-3x a week seems to be the min frequency for decent growth based mostly on consensus.
The reference standard was daily dosing.
Weekly dosing was often suggested by vendors and their products, but these tended to be for general advice based on both CO2/non C(O2 aquariums, which have vastly different rates of growth, well over 10-20X.
What you do not want is feast and famine. So dosing say 1 ppm of PO4 and then have is run out at zero late in the week.
It's better to have the PO4 at say 1 ppm and then maybe drop to say .5 ppm for a day or two, then dosing brings it back up to 1ppm or 1.2ppm etc.
Plant uptake enzymes adapt to the environmental concentrations.
So if the concentration range is say 0.1 to 0.2 ppm PO4, there's a specific set of enzymes the plant makes for low ppm's, these are called High Affinity uptake enzymes. These require more energy to operate. Say 0.2- 1.0 ppm, there is a medium affinity uptake system, these require less energy to operate and can take in more volume of the nutrient.
Then say a low affinity uptake system will operate at say 2- 5ppm of PO4 and above. This is the lower/lowest energy requirement for uptake and the plant can gobble up a good deal of the nutrient for growth without much issue.
Plants can adapt, but ideally you want them to be stable so they do not need to retool and change between these systems. They can do this, but it takes a little time, likely a week or two etc. Soil sources change slowly...........so most never see this, but in the water column and inert sediments, the effect is much more pronounced.
There is also no reason why one cannot dose non limiting ferts daily or reduce or increase them(but there's no real reason to dose more of a non limiting fert) if the plants look happy.
Up to you.
The water change thing can be used over a wider range also.
It's just a tool for managing and keeping things in that range.
This is why planted tanks can grow well still at various concentrations.
But it is easier as far management for many folks to hit the non limiting D range vs say C or B ranges:
D is a much larger and easier target to hit.
Which is why I suggested it to begin with years ago.
As you can see, you can start say in the middle of D........and then simply slowly and progressively reduce the dosing till you hit C. Then you can reduce water changes quite a bit etc. But still have the same growth as D.
This is generally what I suggest. There is little if any risk from over dosing.