works in Friday vs works on Friday

Some examples from the web:

• Mr President, I voted not to work on Fridays in Strasbourg although I am totally in favour of our meeting here.
• It's my contention that going to work on Friday in jeans and [a] T-shirt isn't really getting to the nub of the issue.
• It might have been better and made more sense to vote not to work on Fridays: in fact, I put it to you that to vote in a certain way and then act differently is a display of blatant disregard for our institution.
• His supervisor and co-workers confirm he was work Friday night.
• It turns out I have to work Friday night, so we can't have my little birthday party.
• Anyway, I work Friday flights so I can fit in classes here, but I have to sacrifice world lit.
• I'm going to take off work Friday.
• I want your lab work Friday, okay?
• You saw her at work Friday?
• If Parliament has to work on Friday, then people must be here.
• I found this weird gold pin when I had to work late Friday night.
• Our experts will begin this work on Friday.
• I went to work on Friday...
• Saturday, at least I have to work on Friday.
• I decided to vote not to work on Fridays because Friday was inconvenient for almost all the Members.
• I followed them from work on Friday night.
• And we know that you printed Helen's fake license at Slots of Luck where you used to work every Friday night.
• You know, I totally forgot. I've got a work thing Friday night.
• I mean, when I was working at that yogurt shop in high-school, my boss had me work every Friday night.
• I told him I couldn't work on Friday.

Some examples from the web:

• He works on Friday nights.
• If Parliament has to work on Friday, then people must be here.
• Our experts will begin this work on Friday.
• I went to work on Friday...
• Saturday, at least I have to work on Friday.
• I decided to vote not to work on Fridays because Friday was inconvenient for almost all the Members.
• Mr President, I voted not to work on Fridays in Strasbourg although I am totally in favour of our meeting here.
• I followed them from work on Friday night.
• I told him I couldn't work on Friday.
• So, after work on Friday,
• I was just finishing up work on Friday, and this - this man burst in, and he - he took me into the archive room at gunpoint.
• The party they threw for me at work on Friday.
• It's my contention that going to work on Friday in jeans and [a] T-shirt isn't really getting to the nub of the issue.
• Why don't we give him a full work on Friday morning?
• An official public announcement of the Members of the European Parliament appointed to the convention must be made because the convention will officially start work on Friday.
• Personally, I would prefer to work in Strasbourg, but I consider that if we have decided to work on Fridays - and this seems to me to be the issue here - then on Fridays the quorum needs to be present.
• It might have been better and made more sense to vote not to work on Fridays: in fact, I put it to you that to vote in a certain way and then act differently is a display of blatant disregard for our institution.
• Who wants to work on a Friday night?
• We sign up to work the move on Friday.
• Allan works on Tuesday and Friday nights at the Konbini.