Ideally, every fastener on a vehicle should be torqued. The OEMs do this by the simple (but expensive) expedient of furnishing tools designed to deliver the exact torque needed for individual tasks on the production line, everything from trim screws on up. No one else can afford to do this, so we get by with 'universal'/adjustable tools to take the place of these specialized tools. Very few of us will have every size needed for the same coverage. But most of us don't even avail ourselves of the more common sizes. 'Back in the day' most guys owned a 0-150 ft lb beam type, maybe a smaller one if you were bucks-up, both used for engine ***embly. Everything else just got 'tightened' and that was good enough. Over the years a few more 'must torque' items got added to the list; aluminum wheels (especially with shank-style nuts) and most disc brake components if doing common repairs or maintenance. I use two of mine for probably 80% of what I torque, my 0-80 and 0-150 ft lb wrenches. ***embling a new motor? Then I'll add the 0-200 in lb to the mix (great for sheetmetal valve covers and oil pans), maybe the 0-250 ft lb one. All the others only come out for specific tasks (bearing preload, etc). The 2-36 in lb screwdriver works great for ***embling carbs. Some of the current torque thinking addresses modern and/or race motors more than our less-stressed ones. When you're running close to the edge though, it can become critical to have everything as close as possible.
when torquing head bolts, main and rod bolts I use the same wrench and shoot for middle of the specified toque range, I look for consistency maybe even more than the absolute number.
The Jalopy Journal
