yeah i find if i agonize over getting something right, i could have done 2 more in that time that are good. so i pick my battles and fight for the ones that i "feel" and put the others aside. sometimes months or years later i come back and inspiration strikes i have another go and boom it works... so you never know.
A5 is a cute size. its not too daunting. its why i like the little ones. it feels "safe" to start. A4 and i look at the page and go "oohffff" i have to fill that!