The issue is it wasn't scaled up for the Republic. I get the CIS droids were lower quality than the clones, and that jedi could be game changers, but the rate at which clones died combined with how quickly new droids could be built doesn't add up with how few regular enlists are depicted in both canon and legends. Even if palpatine was playing 4d chess the whole time the rate at which clones died couldn't work with how long it took to actually replace them. Pick any nation in WWI and they likely had a larger army than the GAR at its peak, and somehow they were expected to fight 10s of millions, perhaps even hundreds of millions of droids along with whatever local forces allied with the CIS and keep it up? Going from a months' long siege on world and then just spontaneously teleporting to the next? Not happening unless you have people to fill those boots.

Logistically it makes no sense. Ships and vehicles will need repairs, not every soldier is going to be healed or rested or even fed enough in the course of a day to do anything of use the moment you set down for the next front. Laying siege to a town even in modern wars can take days if there's enough people to protect it and enough reason to not just bomb it to hell, and in star wars things like shield generators can pretty much nullify the risk of an artillery bombardment that would expedite the process. If the clones were defending a locale unless they receive a ton of support from a planetary military, will not be able to fend off the attacking force well enough to be able to leave. Not to mention the Republic had clone garrisons on numerous worlds. The GAR would simply not have the hitting power to take on the CIS in any meaningful way unless they had their own massive numbers of regular beings signing up to join, like 10s of millions being trained, graduated and deployed with regularity.

In WWI France alone suffered almost as many casualties by 1918 as the Republic had soldiers at the height of the GAR in SW.

Also IIRC it wasn't a day for a number of trips, even for larger vessels. For everything that was supposed to happen in the Clone Wars to happen at the scale of which it happened, it simply isn't reasonable. It should have taken five or six years to seem reasonable, but even then who am I kidding if we are talking a galactic scale war.

Also if we go with old canon or to a lesser extent even new canon, droids sucked ass but were decent enough that they weren't completely useless on the battlefield. In Episodes 1-2 and the old animated series B1 droids might as well have been on par with a standard irregular militias in places like the middle east, maybe a little bit worse.