Time weights: Chain or Fixed

Gear menu → Settings → Trading → Time weights. The setting appears only when Option time is Trading.

• Chain (default) starts from the measured weights and lets the chain adjust them: when two expirations’ prices say the nights between them are worth more or less than the weights, Tented scales that span by the ratio, between 0.25 and 4 times.
• Fixed uses the measured weights alone. See Option time for what they are.

If Time weights is missing, Option time is on Calendar. If a stock’s weekend decay looks flat, that is by design: single stocks use flat fallback weights. See Pricing setting is missing or decay looks flat.