mamoo 1. Your thinking I'm like
Bob_P but I kan't type nor spill nor am I on speed to type near as fast as speedy Gonzales. So no dissertations

There are basiclly 3 schools of thought on updateing the TC :
A. emerge whatever -uDN
B. emerge emerge emerge emerge (keeps the electrons in your box from getting fat)
C. and emwrap.sh
Ok A, regular portage, works fine 98-99% of the time. Its gets dangerous though when updates are few and far between. gcc and glibc upgrades that are several rev levels different or major version bumps. gcc-3.3.4 to gcc-3.4.6 can break systems.
Then there is B, robmoss electron dieting plan. If you read the first page it takes 3 emerge systems, the 3rd being an emerge world, to build the TC and the system progs with that TC.
Bob_P swears by emerge emerge emerge emerge. It works for him and Rockhopper & Jackass show his thorughness. Then again part of it might be to cut down the support post. To update your Rockhopper TC emerge emerge ... if you dont dont post. I didnt talk about useing emwrap to bootstrap till some one posted that they had done so with success. Why? I cant and am not interested in running a bootstraping support thread

though it would probably improve my typing.
The same with building the TC once. I did it on the command line and got tired of it. So I put the "1" option into emwrap.sh. My current system started as a stage3-i386 => to a 586 doing the TC twice, emwrap.sh -se once and then emergeing world to my taste. I then, a year later, changed CHOST to i686 and did emwrap.sh -seb1 (TC once + system) and then rebuild the world progs twice. Its what I'm running now. Ive delibertly bootstraped stage3-386 to 686 to see if it works and havent had any probs. I spent a lot of time once trying to come up with the correct build order for the system files so that it would need to be built once like a stage1. Dang if my order didnt end up matching "emerge system -e" minus the TC. So I gave up trying to re-invent wheel.Back to the point building the TC and system once works for me and if it doesnt Ill just build it a second time. Thats my experince, and I still relate back to my P166 days thinking that there has to be a faster way. Hey all this compliling cuts down my seti results.
But even if you build the TC and system files twice and then built the world files, emwrap.sh -W, twice thats just 2 "emerge worlds -e". So its still a lot quicker.
Hope this helps
EDIT I was in a hurry this morning and when I got home I reread the mess I posted this morning. Hopefully this is more readable.