Geek;
It may seem like we do it with everyone and not just on initial contact, but for the most part, that is the only time that we do it. Like you said, less is better when it comes to phraseology due to the traffic load of a lot of sectors. We do have a lot of folks checking in that may not sound like they are. You may also here us telling the to "contact" Memphis Center on yada yadda yadda... Lots and lots of freq. changes... It is not at all uncommon when you are busy to have between 25 and 33 aircraft in your airspace all moving about ....
regards
Scott