DislikedI could say that its more logical to set weekly targets based on multiples of initial risk per trade ('R') but I guess you can do whatever suits you.Ignored
Risk: Amount you are willing to loose per trade, say I am willing to loose 5% of equity/trade and my weekly target is 15% of equity (using the popular 1:3 Risk-Reward ratio).
Now comes practical application:
I have $100, on every trade I am willing to loose $5, now I could loose it on a varying amount of pips (depending on my choice of lot-size), generally the lower the lot-size the harder it is to loose the $5 and the harder it also is to make the $15, lower lot-size would require greater pips (most likely also a higher number of trades to be taken/week) my experience in trading says the more the number of trades the more the frequency of losses.
Actually risk is only really defined when an S.L is set, before that it's 100% of your equity regardless of lot-size. So I have to decide the max S.L I can have on any given trade, which depends on lot-size, not forgetting the number of trades (what governs these decisions?)
As you can see there is no clear definition on lot-size, S.L or no. of trades to be chosen using this suggestion. My method helps me define no. of trades (to a given degree) and lot-size. I believe S.L always varies, as does T.P.
I might be wrong with my assumptions, this is your suggestion, you could shed more light on the method (it could be useful to other viewers).