Fair enough - I can only type about my experience of some years ago.
My income was precipitated by - over three shifts (morning, afternoon and evening) - 20/30 tips.
Ranging fro £1 to £20; the latter was very rare; average £6; over 7 days.
Much more interesting in these prestige hotels is the side business(es) of the Duty Manager - usually, but can be the Head Porter or a long serving hotel fixture.
This chap can surreptitiously procure any service or product, at a price.
For £10 note, I often picked up a small package from a nearby location.
Or delivered a message - in an envelope.
Just one condition- 'the pick-up/delivery' never happened.