It's not about getting a lot of upgrades on them, it's about being able to upgrade them over a long period of time. Once you've upgraded the Palm Hotel to level 10 you've spent less than $12 billion without any upgrade cost mods. The upgrades might take a long time, but that actually gives you the luxury of being able to save cash and not have to worry about what you can afford to upgrade, at times for several days.
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https://docs.google.com/spreadsheet/...owsperpage=250)
Hypothetical situation, you reach a point on an LTB where you can't afford the next upgrade. There is time left on the event clock, war weekend has yet to arrive, you have some cash available that hasn't been donated to your syndicate. Your upgrade options are several short, expensive LTB upgrades, or one long upgrade costing close to the amount of one LTB upgrade.
Do you:
A) Go for broke, and go (game cash) broke, upgrading as many LTBs as you can afford, even though this leaves little or no cash reserve for future needs?
B) Start a long upgrade that won't increase your IPH as rapidly, but will allow you to prepare for future game cash needs without having to worry about building upgrades?
This is bordering on the discussion of why multiple building upgrades isn't as useful a mod as many believe it is, but that should be left for a separate thread.