Range construction is where most study time goes and where most of it leaks. The mistakes are rarely exotic — they are small habits that compound. Here are five that show up again and again.
1. Starting from the solver output
The solver gives you an answer, not an understanding. If you copy a strategy without knowing why a hand raises rather than calls, you will misapply it the moment the situation shifts by one variable. Work out the reason first, then check it against the output.
2. Building ranges you never drill
A range you constructed once and filed away is not knowledge you own. If it is not in your drilling rotation within a week, it will not be there when the spot comes up live.
3. Over-fitting to one stack depth
Players build a beautiful 100bb strategy and then play a session at 40bb. Ranges shift hard with depth. Know which spots you have actually studied at the depth you are about to play.
4. Ignoring the nodes after the first decision
Preflop and flop get all the attention. The turn and river are where the biggest mistakes live, because the pot is bigger and the ranges are narrower. Push your range work at least one street past where it feels comfortable.
5. Treating "mixed" as "random"
When a hand plays two actions at some frequency, that is a signal about how close the decision is — not permission to guess. Understand what makes it close, and you will read the whole region of the range better.
The fix is the same each time
Slow down at the point where you would normally copy an answer, and make yourself state the reason. If you can't, that's the spot to study next.