Mixing it up!

[muscle99]

Hi everyone, I am doing a 4 day split at the moment. Week 1 -3 8 rep max week 4 12 rep max & so forth. Is it best to have a different routine to the one 7 days ago? For example I use Sunday to train chest & biceps. Say :

chest

flat db press

flat db flys

incline db press

incline db flys

biceps

barbell bicep curl

hammer curls

db curl

21's

Each Sunday is it wise to rearrange the order of these exercises? How often should I introduce different exercises? Is it more effective using a heavy weight for 3 sets or a lighter weight for say 6 sets of a particular exercise?

Any advice much appreciated.