Forum:Chakra and handseals

hi there, im new to the forums.

i have recently been caught up with the anime and manga. From my understanding, handseals are used to focus chakra to a certain part of the body. Once experienced with a certain jutsu, less or none handseals are needed to perform the certain jutsu. So why is it in episode 84 sasuke performs chidori with no handseals, yet in around episode 134, before naruto and sasuke have a rasengan vs chidori, sasuke performs handseals to create chidori.

Furthermore, ive never seen itachi perform handseals to create the shadow clone jutsu, yet in manga chapter 387 page 08, sasuke says 'fuck, how did he have time to perform the handseals for the shadow clone jutsu'.

im a bit confused now. can any1 help me? and refer to episodes/ manga chapters. many thanks

tars94