Browndog - it depends on the day and organization, but it can be anything from an urban park trail that needs some clearing and/or repair to a backcountry trail that takes a day or two to hike to that needs the same. Around here, we have half a dozen organizations that focus on different things, from single-use (mountain bike) trails to multi-use (hike/bike/equestrian) throughout the region.
This last crew was one of the backcountry trails that took a day to hike back into the Wilderness to get to. That's hard work enough, with a fully loaded pack and tools, which are all hand-powered, just like your grandpa would have done. The work is hard, and fun, just like you said. Several times we ran into a stretch where 4-6 trees of 12-16" diameter were "jackstrawed", meaning that one started a domino effect, taking down the rest, when they all lay in different directions on top of the others across the trail. It's fantastic puzzle work, figuring out not only which order to cut the trees out, but where to cut them, how to cut them (especially if there's a lot of tension in the log, which there usually is), and how to clear them safely (not let them roll downhill on top of hikers on the trail below). A situation like that typically takes about an hour or so to clear, then we continue hiking up to the next one.
No doubt that there are similar organizations in your neck of the woods. If you and yours are trail users, I recommend reaching out to them and giving them a hand once in a while. It will give you a new appreciation for the work that needs to be done to keep a trail open for general use.