Yeah we were having this conversation in chat a couple of Fridays ago, where you take a few losses in a row and alot of guys go down in there leverage and make a profitable trade or two, and then as soon as the leverage goes back up again the losses start. Some days trading is tough and if your stubborn more often than not, it will hurt. The trick is that on some trades there are those nuances that can show up (that only time and experience will show you them - you will never know all the nuances) but those nuances sometimes are enough to put a dampener on the bread and butter routines that we wish we all could follow. These nuances are usually a function of market conditions on that particular day btw, not necessarily your edges.
Best thing I can recommend, is that if you are trading a basket of say 9-12 'edges' (i use quotations because some people still believe that they dont exist and its all money management - but heck if it was all money management I shouldnt be sweating my entries at all and I should be sweating my exits way more which with real life money isnt the case for me and most of the guys i talk to), after taking multiple hits - sit around a bit and wait for the higher probability edge stuff to pan out. Ya, you might miss out on the move that you could have caught had you followed your system blindly no matter what, but usually waiting for the tried and tested edge is better. What about when you miss the trade that was a winner after the successive losses and your suppossed 'sure' thing' stuffs up? - it has happenned to every seasoned trader, dont worry, drop your leverage and at least get that batting average up or call it a day/a month/(a year in some cases...

). It depends alot as well on your living situation to be able to cope with these scenarios. Its not so simple to say "just follow your system come hell or high water and you'll know if your edges are sound" (thats probably a third of the story), but the main is the conditions and nuances that will pop up and your interpretation of some minor technical point. Very often you go back and re-look at a badtrade to discover that actually your system(for lack of a better word) was right, its that you didnt interpret it correctly. Makes you feel better (but your down in cash), but at least re-examine the stuff ups to fine tune that trading plan. That can take months and months - infact its a good idea to always have your trading plan up on one screen and re-edit some minor technical point that may not show up for another week - but it will be fresh in your memory when it does.
Be prepared to completely throw out half a dozen trading plans in your carrer before you find your style . The on the fly rules that you mentioned means that you have not done enough trading - virtually nothing should be left up to "on the fly" trading. Every part of price action and levels that are active at any one time, you need to know where you stand according to your 'worldview' of the mkt. at the point when your decision time has arrived.