So some how all of my players and I had missed the rule that you can only tick off one stress box at a time.
Our combats have tended to involve a lot of maneuvers to set up aspects with free invocations but I'm struggling to see how you get the space to do that when you can't tick of multiple stress boxes at once to mitigate early instances of damage.
It isn't hard for a wizard to have access to a rote with a targeting of 5/6 and a weapon value of 3. How does anyone survive long against that?
It's also not hard for a mortal to have an assault rifle with Weapon:3, fired from 5.
Seriously, an out of the box wizard can easily be throwing out a Weapon: 7 attack with targeting at 7.
The short answer for surviving against that is to create a situation where they can't attack like that (lots of mortals around if it's a good guy wizard, take away foci, and encourage compels and invokes).
One thing to remember about Dresden combat is once people start getting hit, it does
not last long. Don't think 'whittle down hitpoints,' think 'I need one good shot to bring this guy down.' It's designed that way, and it hits both ways.
Should I be putting more emphasis on the players doing research or set up before combat to get access to temporary aspects from the off?
This is a good idea, yes. Looking into their opponents' weakpoints and strategies can make for a good session in itself, and adds a dynamic to the combat that really helps.
I had players once, a team of wizards, who found their enemies' workshop. They did well enough on their Lore and Investigation rolls to really learn how she operated, so they could later make a spell that totally shut off her magic (this is after said enemy beat up one of the PC wizards one-on-one, of course).
Think of the books and how Dresden wins his bigger conflicts. Yes, sometimes it's by being able to belch flame and fart lightning while he withstands the other guy's attacks, but the big, important fights he wins by exploiting something he'd investigated beforehand.
Your players should be encouraged to do the same.
I'm concerned that if we start dealing with stress and consequences as written, the player builds will start to become focused on spike damage, weapon values and anything else that bumps those attack rolls at the expense of declarations and create an advantage actions.
Then make sure to give them other things to do besides combat. Remember that DFRPG is as much about investigation as it is smacking people around.
In combat, though, a lot of Taran's points are good ones. I would also emphasize to them that declarations and maneuvers are how you
create spike damage -- sure, you could win by just hammering the villain over and over to get past their toughness, but it's more interesting if they're maneuvering for one big blast to take them down.