As such, it's not possible to drive 100 mA through a 50 mA LED even though the average current is half. With smaller duty cycles and frequent pauses, it's possible to drive a lot more current in very short bursts. Not only does the potentiometer allow for hand tuning, but also the frequency can be varied from about 32 kHz up to about 42 kHz. The margin means the desired values of 36 kHz to 40 kHz should be attainable even with variations in parts and wiring. There's a slight change from the official schematic presented above.
Testing indicates the same frequency, voltage range, and power consumption regardless.
On the left is a multiturn potentiometer. The multiturn allows for more precise adjustments and is less prone to shift out of position. Even if it does shift, less change results because it needs to take multiple turns around. Multiturn potentiometers are more expensive, but worth it for timing circuits. A very small infrared circuit can be created with surface mount components.