A hi-lift is most useful when stuck or having a flat in a bad spot. I carry a 4 ton bottle jack with a couple 2x4's and a hi-lift jack. If I have an issue with a tire on good hard ground, I normally use the bottle jack. If it's soft ground, I often jack a bunch of the weight off the tire with the hi-lift, then throw the bottle jack under the axle and get the tire high enough to work on.
A hi-lift (Real one, not the Cheapo Chinese versions) jack is very capable of lifting more weight than you will ever want to lift with it. I've lifted in excess of 10K lbs with one on several occasions. It took all of my 240lbs on the end of the handle to lift the weight. It shortens their service life, but it works and if you are careful it's fairly safe. Just make sure that you remove the handle clip and handle when you are at the height you want. The last thing you want is for the pin to slip and that handle to go beating around looking for something to kill with that much weight on it.
For lighter loads, I leave the handle clip in and use it like you are supposed to.
Stay away from the 20K and up bottle jacks unless you have a semi truck. You don't need all that bulk or weight to lift your rig. A good 6 ton jack will lift anything you want on a rig that grosses 10K total weight since that weight is usually spread around to 4 tires.
A couple 2x4's are more useful than a 4x4 block since you can stack them at your needs, vs having to dig into pavement if your 4x4 block is too tall.