I'm not sure how much is inefficiency due to tea/fag/gossip breaks and how much due to lack of equipment/people. In one project I worked on, I was initially taking 6+ hrs to prepare some tissue. The protocol that the boss insisted I follow to the letter meant that one homogenisation step then required the equipment to be placed on ice for 20mins to cool down again before it could be used again. Of course, it didn't occur to the boss that it would take much less time if used in a cold room. Another time, I was regularly sitting down to eat lunch after 3pm because the dry ice I needed for another time consuming protocol used to arrive quite late in the morning. One of my friends used to regularly put in 12-16hr days purifying proteins - the first late night would mean she would be late in the next morning, which would then lead to another late night due to a long work day.
But, a lot of this is macho posturing, particularly within academia. My friend's long days could easily be reduced for her by either her boss starting off the next day's purification step (so that it was already running when she arrived) or by (shocking idea here) hiring another pair of hands. I know of other people who came up with protocols with long incubation steps so that they could get a break during the day (even if it was for something superfluous like eating). But, once they leave the lab, others are told to follow the protocol and it gets set in stone. You will do it this way, even if it takes you until 9pm because this is how it's always been done. (And, as far as some PIs are concerned, you being the lowly student/postdoc/whatever do not have a life outside of the lab).
Of course, there are lots of people willing to take part in the charade - I've worked under people who arrive early and claim to work. Most of the time, they sit there looking up non-work related stuff on the internet or having coffee in a secret hidey-hole, somewhere they can't be found easily. The bosses though love them because all they can see is someone (or their stuff) being there, appearing to work. Sad thing is, I've also been criticised for not being there at all hours, even though I had finished my work within normal (9-5) hours.