The common follow up is that I make the decision to pick an all-inish rush build or a really unsafe macro build. Either I do it because of arrogance; I don't think he's worth my time, or I do it because I fear losing a mid/late game to him. The very possiblity that he might be better than me at my own forte scares me. But there's absolutely no logic in these choices and the more often lead to defeat than victory.
If he were in fact better than me at those things there would be a ton of stuff to learn from the game(s). I rarely get to play players better than me but when I do I improve alot from those games, so throwing away one would be such a stupid waste.
On the other hand, if my asumption is correct and I'm the better player then I don't have much to fear from entering mid-game, even if I do so with a slight disadvantage. Winning is always prefered to losing when playing worse opponents.
The second bane of my gameplay is the scar left behind by numerous of games against uncreative opponents that are doing their best to learn 'that new macro build'. When my opponents all play the same I start to expect them to play that way. And when I finally come across a free-thinker I'm too stuck up in my habits to counter his sudden move.
Even if I know the counters to nearly all cheeses I need to know that they're comming a certain time before the actually come in order to be able counter them. However, scouting is the first thing that suffers when your opponents get repitive.
Falling into those bad habits get even easier when I'm tired, which often is the case on weekdays. Tire also clouds my mind in other ways. Judgement suffers and I'm less likely to percieve the threat of certain things.
Just yesterday I had a guy lift a factory into my main. I knew it was comming all along cause I had seen him send out a second scv to the direction where you normally build the proxy factory in order to easily lift it into the main. I could have pulled off a drone and prevented him from landing the factory - but I opted for a sunken. The cost of those two alternatives would most likely have been the same. But I had forgotten the nature of the map I was playing, so instead of one sunken I needed 3, and that only to defend my main. Need I say I lost the game? Badly too.
Another common situation is when my opponents are academy rushing. I start to relaise that somethings not right - he should have expoed by now. Yet I don't want to lay down those creep colonies because they would delay my spire five to ten seconds. And when he finally moves out it turnes out the distance inbetween our bases was not really long enought to give my sunkens time to complete. And I die to an academy rush, ain't it pathetic? Even if he had in fact done an expand it would have been so late that I easily could have delayed my spire alittle without getting behind.
Basicly what I've wanted to say with all this are these things:
1: Know your strenghts and shape the game so that you have use of them.
2: Avoid asumption and always be prepared for something new. Don't let bad habits get the best of you. There's no excuses for not scouting.
3: Take every threat seriously. If he dedicates his whole build to a rush, then why should you not dedicate your whole build to countering it?
4: Being arrogant is the easiest way to play below your potential.
(5: Don't play important games when you're tired and/or have cold hands.)