Hard to tell for sure. At the beginning of the war there likely was incentive to hold back as the assumption was that Russia will just overrun Ukraine and/or they'd more or less willingly join Russia as a country. In that scenario we would've just given Russians loads of western technology to study/copy without anything in return.

Reality was of course different than assumptions and now it seems quite inevitable that Ukraine will win the whole war, so I agree that it would make sense just to give enough hardware for them to end the war quickly. But then there's the threat of nuclear weapons and maybe more importantly the manufacturing capabilities. It's a lengthy process to evaluate what can be given so that it doesn't hurt origin country too much (like Finland with our artillery/tanks, we need those ourselves) and how long it takes to replace the donated gear. The whole western world was struggling to even manufacture enough just artillery ammunition and in the scale of world wars the frontline is relatively short.

Then there's capabilities of AFU. They're of course proven their skills over and over again, but training for the new weapon systems take time and specially US made systems depend on ridiculous amounts of logistics which would cause challenges to every other military on the planet and even more for ex-soviet country.

And on top of that there's politics and money. Someone paid for that hardware and weapon exports in general is a controversial topic even at peace, so everything is a bit more complicated than to load a train and send it to front lines. Apparently it's easier politically to give something small at first and increase the pace slowly. "We already gave 10M worth of hardware, what's another 2 on top of that" kind of thinking.

But all this is of course just a speculation from an armchair general.