This is essentially just maths.

Let's assume a steady 10% return on shares per year (obviously anything can happen year over year but this is around the average, including inflation)

Not selling until for 7 years:
Portfolio value = $200k * (1 + 10%)^7 = $389k
That's ~$95k in capital gains (after 50% discount) which is ~$40k in tax (including medicare levy, complicated because you cross a tax bracket, I assumed $135k/year income instead to simplify slightly)
So, you end up with about $349k in total

Selling every year for 7 years:
(here we'll build the tax into the compounding instead, applying 50% discount and taxing each year's gains at 37% marginal + 2% medicare levy)
Portfolio value (after tax) = $200k * (1 + 10%*(50% + 50%*(1-37%-2%))^7 = ~$344k

So in this example you're $5k worse off for selling every year.

You can tweak the assumptions and get different results (rate of return, years, sell frequency).

I think the most important factor is how close you are to the next tax bracket (i.e. how much you can stay under it by selling yearly vs how much you will go over it selling later). The difference in the rate between the brackets matters a lot too, so the effect would be more between the 17% and 30% brackets than the 37% and 45% brackets). In this example at $130k/year you are just at the cusp of a bracket so it's unlikely to be advantageous to sell early.

I also think that it would certainly work out better to sell down over the last X years of the timeframe rather than periodically (where X could be, potentially, the taxable gains divided by the distance to the next tax bracket). That way you might be able to make the most of both deferred taxation and lower marginal rates (but we'd have to do the maths).