A problem with mechanical systems... when to bet, what to eliminate?

I have numerous mechanical systems that are quite good.
Here is an example of one..

BETS RETURN POT% WINNERS S/R APW
126 $192 53% 24 19.05% $8.02

Now normally after 100 bets, 50% POT, I'd lock this system in.
However, I can break it down into 8 sub-systems. They are..

BETS RETURN POT% WINNERS S/R APW
10 $12.30 23% 2 20.00% $6.15
26 $20.00 -23% 3 11.54% $6.67
9 $22.10 146% 2 22.22% $11.05
5 $6.00 20% 1 20.00% $6.00
14 $40.20 187% 5 35.71% $8.04
19 $20.10 6% 3 15.79% $6.70
23 $48.60 111% 5 21.74% $9.72
20 $23.10 16% 3 15.00% $7.70

I wouldn't back a system until at least 100 bets are in it, with at
least 30% POT. Which the system as a whole has achieved.

Would one be happy backing the system as a whole knowing that
you would be confident that at least 4 of the sub-systems will not show
a decent profit in the future based on other data I have? Even though the
whole system is returning 53%, after over 100 bets.

Or would one wait until each sub-system has 100 bets too?
That would take another 15 months at least, I am too impatient for that.



Now,
Another problem with mechanical systems, I have many systems showing a small 1-10% profit after 300 bets.

Example :
BETS RETURN POT% WINNERS S/R APW
260 $289.90 12% 33 12.69% $8.78

I read somewhere that you cannot filter too much of a system because
you would not know then what could be anomolies in the system that you
are keeping. ie, just a good run.

Now if I was to eleminate 150 bets in this system using 3 common-sense filters, those 150 bets returned only $100. Leaving the system with the following :

BETS RETURN POT% WINNERS S/R APW
110 $185.40 69% 22 20.00% $8.43

Now surely after 5 months watching this system (after the 3 filters)
clean up continuously month after month, a mechanical system can work
no matter how heavily filtered it is? Correct?


Last question, mechanical systems. How many bets in the database would
each of you be happy with before you start betting?

It's ****ing me off because I am not confident enough to bet on my selections
religiously yet. All the doomsday articles I read make me unsure if I should
begin yet.