with proper digital machine, 28 lbs is 28 lbs. on crank machines, 28 lbs is like 26 lbs (or sometimes less, or sometime more...)
I would say it depends on the tension the person was using before. If they were using 24lbs or less then I think they might have some problems adapting. They would be better off increasing their tension by 2lbs over what they are used to, and then increasing it by 2lbs each time once they get comfortable.
I would have to say 28lbs is to high for an intermediate player, playing at that tension requires very good technique and timing... something which intermediate players are not always perfect at, which can lead to injuries in the racket arm shoulder and elbow due to possible overhitting. As suggested, probably best increasing your tension gradually until you come to tension you feel comfortable with.
I'm intermediate player. I had ~ 26.5lbs, it was a tad too high for me. So expect 28lbs would have been really really worse. We as intermediate player still rely on the bouncing effect which is a nice support. With these 26.5lbs respective 12Kg I didn't get enough bounce effect for clears and smashes. It took a month until the string was really playable for me. Now I go for 11.5Kg (respectively 11 and 12, but don't ask me which one is cross and main ) High tension gives you more accuracy but will make your smahes and clears much worse if you don't have the strenght or a proper technique. If you don't have both of them, you will be lost with 28lbs That's just my opinion. A friend of mine stringed two rackets with 13Kg (~28.5lbs). At the beginning he said it's not a problem at all, it just needs some adaption. But now he went back to 11Kg. You'd better test 28lbs on a backup racket if you really want to. Or just start with 2 lbs more than your actual tension.
In my experience there is a strange range of tension in which I get absolutely no power. For me that range is from 20-22 lbs. It's a small range, but it's still there. I will outline what each range does for me: 20-22 lbs. No power, clears don't go end to end, dull sound, netshots and dropshots too high. 23-25 lbs. Good power, clears can go straight end to end and most of the time crosscourt corner to corner, good sound (higher pitched), netshots and dropshots are a little tighter. 26-28 lbs. Good power (with 60-80% of full power) and excellent power (80% of full power). All shots go the distance, netshots/dropshots are still tight. 29 lbs. + I can't seem to generate too much power, probably not flexing the stringbed enough with every shot. There are moments of great power, but generally too much effort required if i have to hit it so hard during every rally. Of course the pitch changes as you increase in tension. The smash sounds higher pitched at the higher tensions and it's awesome. People don't expect it. It takes more effort to generate power at higher tensions, but then the repulsion is also much more noticeable. It also helps if you have a more flexible shaft, especially with a slower swing speed. A faster swing speed would require a stiffer shaft to generate adequate power and angle.
agree in general. i find that it also depends on the string and of course matching with the racket. stiff, or heavy, or head heavy racket tends to favor higher tension. light, or flexy, or head light racket tends to favor slightly lower tension. i think it has to do with matching the response time of the string with the response time of the racket (stiff matches stiff), and also lighter weight / head weight don't have enough momentum to induce enough force to bend the stiff string.
Although I know of a few advanced players with powerful forearms and fast swing who prefer playing with head light flexy rackets strung with bg66um or 80 at 28-29lbs... Somehow their stroke has a whipping action to it which works in this strange combination.
I usually have my head heavy rackets (Z-Slash and Voltric 80) at 25/26/27 lbs I'm 16, so I dont have a lot of forearm power and developing, strengthening the forearm to cope with higher tensions. If you want to go to 28lbs go up, 1lb at a time. I started from 24lbs on my Voltric 80 and went up to 27lbs but each time I snapped my string I would tighten it by 1lb