Here is my opinion. You can have 3000 spells in a macro, but why? Why have to push ALT UPPER SHIFT OTHERKEYBOARD FAMILYROOM Spell to just cast a spell. Just make an attack macro and a healing macro. Make a pet is tanking macro and pet is assisting macro. You can also use focus so every macro is simple, and relatively short. I don't have ANY targeting or names in macros other than in my focus macro. Do it once and then you only have to do it when someone dies. I don't even change focus when my main dies. The main can still target someone and the alts still kill whoever the main has targeted. Then they just res him after the fight.

With the macro you tried to make shorter, think of semi-colons as the THEN part of a if then statement. It only casts the part after the ; if it can't do the first part. So:
/cast Spell 1; Spell 2

Is NOT the same as:
/cast Spell 1
/cast Spell 2

People use it like:
/cast [harm] Spell 1; Spell 2 (only casts spell 2 if noharm)
I just make a new line, it makes things easier to read. If you need the extra space from the /cast, you are making the macro too complicated.