Starting small and gradually scaling up creates multiple psychological adjustment periods. Each time you increase position size, you must readjust to new profit and loss magnitudes, essentially forcing yourself to adapt repeatedly to what is fundamentally the same trading setup.

Position sizing is an integral component of any trading strategy, as carefully developed and integrated with entry and exit rules. Artificially constraining position size means you're not actually trading the strategy you tested, but rather a different system with modified risk parameters. The psychological challenge of watching larger P&L swings needs to be addressed eventually.

Scaling up gradually doesn't eliminate this challenge; it merely fragments it into multiple smaller but prolonged adjustment periods, potentially extending the total psychological stress over a longer timeframe. A strategy's expected performance metrics are based on specific position sizing rules. Trading at reduced size means operating outside these tested parameters, potentially leading to premature strategy adjustments based on statistically insignificant results.

The compounding effect of multiple scaling adjustments can obscure the strategy's true performance characteristics. Each size increase introduces a new variable, making it harder to distinguish between strategy performance issues and normal statistical variance.

Trading at reduced size can also create false confidence. Early success with smaller positions might not accurately represent how you'll react to full-size trades, potentially leading to overconfidence before the real challenge of managing full positions begins.

Scaled deployment extends the period during which you're not collecting meaningful performance data. Since the strategy's actual risk-adjusted returns can only be properly evaluated at full size, starting small delays your ability to validate the strategy in live trading.

By deploying at full size immediately, you face the complete challenge upfront, allowing you to focus entirely on adapting to the strategy's true characteristics rather than managing an artificial scaling process. This approach, while potentially more stressful initially, provides clearer feedback and a faster path to strategic competence.