What technique may be used for the longest period of time with a client who has sluggish skin?

Pétrissage is the technique that can be used for the longest period of time with a client who has sluggish skin due to its effectiveness in stimulating circulation and promoting lymphatic drainage. This technique involves kneading, squeezing, and lifting the skin and underlying muscles, which can lead to increased blood flow and the release of toxins from sluggish tissue. This not only helps improve the overall appearance of sluggish skin but also enhances its vitality and health.

The sustained pressure and rhythmic movement associated with pétissage allow for deeper manipulation of the muscles and connective tissue without causing discomfort, making it suitable for longer treatment durations. It's also beneficial for introducing products into the skin, as enhanced circulation can help with better absorption.

In contrast, effleurage, while also a beneficial technique, is generally lighter and intended as a preparatory or finishing method rather than a deep connective tissue treatment. Tapotement (percussion) is more invigorating and stimulating, making it less suitable for prolonged use, especially on sluggish skin, as it could lead to overstimulation. Shiatsu is a more specific technique that involves acupressure and is not typically used for extended periods in the context of skin treatments. Thus, pétissage is the preferred technique in this scenario.