My size per DARWIN evolves between 200 and 400, and is managed "per unit": 1 unit = 200 €
I never take profit on those 200 (except quarterly rollover)
I set take profits only to exit arbitrages that are made in plus of these 200.
I check the portfolio every end of day before the close to see if some DARWINs in my portfolio have experienced enough volatility to take an action manually.
A quick eye only for "maintenance".
I use to re-adjust my pending orders once a week.
Also, if there are set of rules well defined in this model, there is a part of personal appreciation, in the sense that I adapt my agressivity according to the general behavior of the DARWIN.
ex: I can made several arbitrages per week on $KWC, because it works with huge volatile swings and so most of the time, you can play the mean reverting on 1.5-2% easily after a big trending day or 2 when you know the guy - and the market - is just about a nervous breakdown hehe).
A contrario, you cannot apply this methodology to "pipspeckers" because tomorrow's returns won't have any link with today's loss/profit.
Let's talk about the vwap tomorrow, didn't have a dinner yet