In or Out first?

For bigger commercial jobs (colleges) which are done once a year, i've always wondered which is more effective/quicker to do first. Inside then out, or the other way around?

What would you recommend and why?

Outside first, then you can check your work from inside after.

Outside first because of what @Nudel said, unless it is raining heavily or people are due inside later. 

I used to do a dental surgery that was fitted with secondary double glazing. It used to do my head in trying to work it all out.

Outsides first. Then unlock and slide back the inside windows and clean the inside of the outside panes. Then slide the inside windows shut, unlock the outside panes and slide them back and clean the outside of the inside panes..... you get the idea.

It wasn’t too bad when I started the job as one of the nurses used to come in early when I was due so I could work unhindered. It became a real nuisance when the surgery came under new management and no one was willing to come in early on that day. I was then expected to do all of the above whilst the surgery was in use. Right embarrassing!

I was glad when that job came to an end.

We do the outside first then the insides no particular reason why but if you do get a leaky window on the outside it won’t get runs on the clean inside if that’s done last 

Inside first 

Always good to get the worst bit out of the way first.