New owner operators might try to put off some work until it is absolutely necessary.
Sometimes, it makes sense to be proactive. For example if you have a truck with 100's of thousands of miles and you need to change the clutch out, you might as well change the clutch brake and maybe resurface the flywheel. Change the rear main seal if it's leaking at all.
(I changed the clutch without changing the rear main seal. Dumb. But a 'great mechanic' would have suggested it. I'm learning and it's why I'm sharing. lol.)
Thoroughly check the pressure plate and throw out bearings, etc.
Ask your mechanic if there are other things you should consider doing related to the work you're already doing.
Remember, although it will cost more to do additional work, it's much cheaper to do it while you're in the shop and down already than to take time off again or breakdown because of something you could have been proactive about.
Also, take the clutch and clutch brake or rear seal example. You already have the transmission down to do the clutch which is mostly labor. It would only minimum time to add the clutch brake and real main seal to the job.(By the way change the clutch brake over to a 2 piece)
If you have to go and replace the clutch brake later it's not a 2 piece, the transmission has to be dropped again.
So instead of it costing you $1500 to do clutch and clutch brake as one job, it could cost you $2500 to do it in 2 jobs plus downtime from running again.
On the proactive front, look closely at all of the hoses. Make sure that they are not old, worn, weak or of course leaking.
If they are old and cracking go ahead and replace them if you have the extra money. It's a lot cheaper than one bursting while your on the road.
Also, don't just check the hoses under the hood. I had the air hose that runs to the trailer and the water hose that goes to the transmission cooler burst. So be sure to check those too.
That said, this maintenance video is deeper than just maintenance on your truck. It's about several types of maintenance that affects your bottom line which is especially important with slim margins.