Slings
Young Burgundy Goliath Birdeaters usually eat more regularly because they are growing and moulting more often. Offer small prey to Theraphosa stirmi in sensible portions and remove leftovers before they spoil.
If a Burgundy Goliath Birdeater sling suddenly stops eating, premoult is one common explanation. Keep water available and do not keep adding live prey.
Juveniles
Juvenile Theraphosa stirmi can normally take larger meals than slings, but the interval should still follow body condition rather than a fixed weekly rule.
If the abdomen of a Burgundy Goliath Birdeater already looks very full, wait before feeding again. More food is not automatically better husbandry.
Adults
Adult Theraphosa stirmi can go much longer between meals than fast-growing slings. Offer suitable prey, then let appetite and abdomen condition guide the next feed.
A large adult Burgundy Goliath Birdeater does not need to eat simply because seven days have passed. A healthy tarantula can tolerate gaps that would be unusual for a mammal.
Premoult and fasting
When Theraphosa stirmi appears to be in premoult, remove live feeders and stop offering more until after the moult and hardening period.
Food refusal in Burgundy Goliath Birdeaters can also follow a rehouse or occur with mature males. Check the whole context before changing prey or feeding more often.
Simple records
Record feeds, refusals and moult dates for Theraphosa stirmi if you keep several spiders. A short note is enough to show whether a long fast is unusual for that individual.
Those dates are more useful for a Burgundy Goliath Birdeater than forcing every spider onto the same feeding calendar.