4 wheel align will check caster/camber/toe and all 4 wheels and adjust front settings while taking rear settings into account. The Focus has rear toe adjustability from the factory and depending on mileage and wear it may be time for rear camber adjustment (using bolts or adjustable arms, as well as spring replacement as rear camber will become more negative as springs sag).
Given that this is probably a 2012 Focus, a full 4 wheel alignment is due. Align to the center thrust line, set all settings that adjustable to middle of specs except front toe. If possible, front toe usually should be set at zero to reduce tyre wear. Keeping all four wheels on the same level of tracking will reduce tyre wear and noise over the long run.
if your tires wore evenly and had a long life, then your alignment is probably fine.
if you take it in they probably wont have to adjust anything as it will be "on spec", but they'll take your $$ anyways.
However, it is an opportunity to take it in and get a custom alignment. 1/8" maximum combined toe out in the front, 0 (zero) toe in the rear. this is the best combination for handling and long tire life.
ask if they do custom alignements, if they don't find another place. the Ford "spec" is too broad and can contribute to tire damage.
Sorry should have looked at what you drive. For some reason I assume everybody drives an older car as that's what I'm always paying attention to. If you don't have any abnormal wear on your tires, it steers straight on the highway, your steering wheel is straight, and you don't recall hitting any nasty pot holes or curbs, I wouldn't do an alignment 'just for fun'.
If someone comes in requesting an alignment and test drives well and it's "in the green" or in spec, we'll perfect the toe at the very least. If caster/camber are barely in spec and don't require modification to adjust we would make the adjustment as well, but if they were .05' off of perfect they probably would not get touched. That's 5 one-hundredths of a degree. It only takes a minute compared to setting the alignment up in the first place. If they require drilling out strut tower spot welds or eccentric bolts we'd give the customer the option. I wouldn't change the alignment off of Ford's specs unless it was a dedicated track car. They will typically provide the best combination of tire wear and traction characteristics in even aggressive daily driving.
I'd like to add that what's been seen over the years is that Ford's specs on rear toe in tend to allow a bit too much when taken to the extreme or slightly over.
One recent poster had an alignment where the front was done & the rear left alone. Rear was at .30/.35/ ttl. .65. Specs on the sheet called for max. .35 /side, ttl .60. That is slightly over allowable, maxed out on toe in.
A number at the other end of allowable (.10 side) has shown to give the best tire wear & good handling, so I'm afraid if left alone that poster would end up with the rear tire wear issue we see posted here often.
Front at zero to minimal out fits in the allowable range & is easy to get from a shop. That's exactly what that poster got on his (zero).
You'll seldom see perfect numbers, but CLOSE to zero erring to the outside (negative) works in front & CLOSE to .10 erring to the inside (positive) is what we look for that IS within the factory range.
Depending on where you're at all that attention to detail may not even matter that much. I buy cheap 50K tires and only a pair at a time cycling the new to front and front to rear. The tires may approach the mileage wearout number but will always heatcrack first to be too dangerous to keep driving on, at least for me. Here in Texas. Buying four tires at a time proved out to be WAY more expensive, you pay bigtime for that cushybutt smoothness all the time. I was losing tires from damage that were still close to new. I pay for no road hazard and repair all flats myself so even more cash saved. Not for everybody though.
There is absolutely nothing you can do to get rid of the problem of backs wearing faster than fronts because of natural frequency oscillation. No weight back there to damp it out like old school rear wheel drive cars did. Balancing slows it down but will not stop it all. The tires begin to wear out of round and you'll help some of that by rotating frequently which I quit doing as the tires will be making noise and bumping right about again at suncracking change time anyway. It was easier to simply give up and cost nothing in tire life at all doing so. Commonly the rears will be destroyed by a nail maybe 40% of the time anyway, the morons around here dump all their construction work nails on the highway and laugh about it. It's nothing to have three plugs in a tire.............