Even in brute force, pruning helps.
Bound checking: If the current partial solution already exceeds a limit, stop.
// Subset sum: if current sum exceeds target, prune
if currentSum > target:
return
Ordering: Try more promising options first. If you find a solution early, you can potentially stop or prune more aggressively.
Symmetry elimination: If problem has symmetry, only explore canonical representatives.
Example: Placing identical items. Instead of permuting them, only consider sorted placements.
Pruning doesn't change worst-case complexity but often dramatically reduces average case.