As written above, average lawyers don't get biglaw. This is important to understand since you're thread title suggests that all law grads experience biglaw when, in fact, only a small minority do.
Yes, a better title would be "How much time does the average lawyer, who actually worked in biglaw at one point, work in biglaw?"
Yes, but a better answer would involve answering the op's question rather than just playing semantics and word games. I have no problem with people not knowing an answer, but when people make post like your question should say this word or have two commas instead of that word, it does not help at all.
Many people are law students, and semantics are a rather big deal in law (and the LSAT, too, for the 0Ls on these boards).
You asked about "average lawyers"; so, some people had a good time noting that average lawyers don't usually make biglaw (if we look at the average law student, he/she probably goes to a TT/TTT. Given the bar failure rate, the average lawyer is likely from a low T1/TT, and not at the top of their class, and so is not likely to be in BigLaw.
A better question would be, "What is the median/modal length of time a lawyer spends in their initial BigLaw firm?" Being in BigLaw is then an assumption, and we then argue about trends and such.
For that, what I have gleaned from TLS is that:
There is a high burnout rate. 80% drop out before year 5, and there are 20-30% attrition rates beginning from year 1 in firms before that. Most burnouts leave after 2-3 years, with those associates not on a partner track leaving after year 4-5. So, you would probably see two major waves of departures- the transfers/burnouts after 2-3 years, and the guys who realize they aren't making partner later on. Plus the high attrition of a high-stress job that requires you to devote tons of time.
I left out average because the few who do make partner can have 20-40 year careers, bringing averages up considerably.
tl;dr Don't expect to spend your entire career in BigLaw, even if you get it. Even those of us who are gunning for it know burnout is a real possibility.
My question was:
"How much time does the average lawyer spend in big law?"
Normal people would understand that this means of the lawyers who are in big law or make it into there, what is the average amount of time they spend in it. Given that these people are able to decipher incomprehensible LSAT hocus pocus bull caca where FAR more vague questions come up in the arguments, it surprises me that someone would want to come up with ha ha, the average lawyer doesn't make big law. Seriously, what reasonable law student would think I am trying to ask some kind of trick question or gotcha questions. What are these people going to do when their boss ask them a straightforward question, come up with these kind of bull shit answers when they do not know the answer. That's a sure good way to piss of the people you work with and line yourself to be laid off ITE.
Even your new question:
"What is the median/modal length of time a lawyer spends in their initial BigLaw firm?"
Is still open to the same criticism, as one could argue the median lawyer does not spend any time in big law. Playing these kind of word games are silly and waste forum space, waste my time, your time and people reading this time. People playing these kind of word games are really just trolls, and the mods ought to crackdown on them, because more often than not, they contribute nothing to conversation/forum, and they have a pattern of posting these useless responses in every thread as they know nothing. Yes I may know very little about big law, but at least I keep my mouth shut and don't go around into every big law thread and criticisize the wording of the question of the ops when I have nothing to contributr. In fact these trolls are driving away the few knowledgeable posters who actually make useful post in this forum.
Now I am not saying you are one of the trolls, but you just have to look above in this thread to see them. I actually found the 2nd part of your post informative.
So what do those who drop out of big law by 2-3 year and 5th year mark do afterwards? Do they go to other big law firms, or completely leave big law? Do they stay in law or just leave law altogether? And if they leave law then what do they do?
Whats TTT (tier 3)?