I get a couple 10min intervals, several short power climbs, LOTS of stoplights, and a few sections where, if I go fast enough, I can make it through a long series of timed light cycles without stopping. It's almost perfect for training. If I take an alternate route home, there are a couple 20min intervals and then it turns back into short stoplight-climbs for the remainder. A given day commuting will generally have me at around 150TSS. I can EASILY exceed my goal weekly training loads and become extremely fatigued by just commuting every day. I prefer to take a rest day on thursday (ride the bus and catch up on reading instead), then easier day on friday and do my team training ride(s) on the weekend (or race). This kind of intensity is important to me because I'll often go on a business trip that has me off my bike for several days in a row, unless I can manage to bring my travel bike and get some riding in, but that's always a bit tough.
For ME, commuting is terrific training.
I just drive to work
Bottom row: 300,000 risky acts that don't necessarily result in anything bad (not looking before you cross the street, doing electrical maintenance work without proper PPE)
Next row: 3,000 near misses where you suddenly become aware of how close you just got to an incident (almost get hit by a dumptruck when crossing the street, or accidentaly reduce a critical system to N due to human error)
Next row: 30 minor incidents/injuries (a rack of servers offline, minor burns from a small arc flash)
Top row: 1 major catastrphe/fatality (whole datacenter loses power, individual gets electrocuted, etc)
Recognizing that we can never completely eliminate human error, we use various risk mitigation techniques to simply reduce the number of risky acts, which should filter through the 'pyramid of doom' and hopefully eliminate most of those 30 minor incidents, and if we're lucky, totally eliminate the 1 major event.
Speed is a terrible metric for training. At the very least, get a HR monitor. This entire thread is conjecture as we don't know your route, the wind that day, or how hard you're actually working. 26mph with a tailwind could mean you're barely working at all, whereas 26mph into a headwind could mean threshold efforts.
There are numerous stickies/threads on how to train with and without power, I suggest you read them. If at all possible, just for your own comfort's sake, look into keeping a stash of stuff at work to cut down on the amount of things you carry. I've used to have a 40mi commute I did 3 times/wk and it was a huge quality of ride improvement to leave the work laptop, a change of clothes, shoes, and shower (if you have a shower) stuff at the office, rather than lug it around in a backpack.
aaronmcd, here is the sticky I mentioned. You can click through it to find a HR zone chart to use in lieu of power data (though HR is not the best metric for training).