There are many expressions in English that have double words. Here is a partial list with examples of how they’re used:
hours and hours – many hours
It took him hours and hours to do his taxes.
days and days – many days
It rained for days and days.
weeks and weeks – many weeks
He had been working for weeks and weeks on the project.
months and months – many months
They’ve been trying to sell their house for months and months.
years and years – many years
She’s been renting that apartment for years and years.
time after time – every single time
He keeps helping her time after time.
time and time again – periodically
He returns to Vancouver time and time again.
hour after hour – one hour after another
He studied hour after hour with no break.
day after day – one day after another
It kept raining day after day.
day by day – each day
She has no future plans; she’s just trying to live day by day.
week after week – one week after another
Week after week she stays at home and doesn’t go out.
month after month – one month after another
He would ask his parents for money month after month.
year after year – one year after another
Year after year the rent on their condo went up.
little by little – gradually
He started to lose his hair little by little.
again and again – repeatedly
She called his name again and again, but there was no answer.
on and on – continuously without stopping
He talked on and on about his adventures in Indonesia.
over and over – repeatedly
She kept saying over and over how lucky she was.
more and more – a little more each time
Every day she likes him more and more.
less and less – a little less each time [uncountable nouns]
As time went on, he became less and less interested in art.
fewer and fewer – a little fewer each time [countable nouns]
As time went on she made fewer and fewer typing mistakes.
better and better – a little better each time
Every day he’s feeling better and better.
worse and worse – a little worse each time
My stomachache is getting worse and worse.
harder and harder – a little harder each time
It seems to be getting harder and harder to find a used CDs store.
bigger and bigger – a little bigger each time
Vancouver is getting bigger and bigger.
longer and longer – a little longer each time
The waiting time for a trial date is getting longer and longer.
smarter and smarter – a little smarter each time
His grandson is getting smarter and smarter every year.
stronger and stronger – a little stronger each time
By working out, you’ll get stronger and stronger.
round and round – in circles
The children turned round and round until they fell over.
all in all – considering everything
All in all, it wasn’t a bad movie.
word for word – each word the same, exactly
She told him what her girlfriend told her word for word.
step by step – all the steps necessary
There were step by step directions on the back of the package.
item by item – each and every item
They had to clean everything item by item.
pound for pound – each and every pound
He can match his brother pound for pound.
street by street – every street
The police searched street by street for the missing children.
face to face – facing each other
Their first face to face meeting was at Starbucks.
shoulder to shoulder – touching the shoulder of the one next to you
The union members stood shoulder to shoulder facing the angry mob.