some missions will let you play them however you want but most are scripted and will fail for many reasons, rockstar created a whole bunch of fail text messages so you would be forced to complete the missions as they intended you to.
In GTA IV you could choose how to approach almost every mission such as scoping out the mission area with a sniper rifle to stand a better chance before going in guns blazing, only mission I remember that was like this was where trevor attacks the o neils ranch.
There were a number of car chases in IV and the EFLC where no matter how much you shot the guy he didn't die until a certain time. People have a serious nostalgia filter with IV.
gang wars aren't in GTA V
I declare myself winner of this argument.
If you're talking about the gang wars and turf missions in SA; those were some of the most boring and tediously repetitive tasks in the history of GTA. So they're not missed one iota by me.
They were fun sometimes but it did get tedious trying to take over little square of purple and yellow. Drug wars and gang wars in TBOGT and TLATD were much more fun.