Used other than figuratively or idiomatically: see for, days.
for days on end
The argument went on for days: they just couldn't agree.
(US, Canada, informal) For a large amount or distance; a lot.
Her legs went on for days.
(US, Canada, informal) To a great degree; very much.
Synonyms: all day, as the day is long
She has legs for days.
That kid has charisma for days.