What does it mean to "follow your plan"?  You determine your sweet spots and your targets/support levels from your homework the night before and the next day you execute your plan.  Initially, this means these are the only levels you trade.  Not, on-the-fly sweet spots intraday.  If you hit a sweet spot, make some good money (10-20 points), and want to gamble some of it on a non-plan-determined sweet spot, then that's a risk you'll have to weigh.  If you aren't already up on the day and don't have the market's money to gamble with, do not gamble on on-the-fly sweet spots.  That would be the exact opposite of "following your plan"!