Can you fill the printed customs form to save time in Canadian airports?

It is possible.
Legally to enter Canada you need to give one or the other.
I have got into Canada with only the hand-written form within the last year.

However, it is also perfectly legal for them to deny you entry for any reason at their discretion.

"It is ultimately at the Officer’s discretion, whether or not they allow you to enter."

They will not likely deny you entry (though they're allowed to, if they find you suspicious enough, and keep in mind some of them are not very smart). But if you're at an airport like Vancouver, where everyone else entering has the kiosk-generated form (with the picture of your face on it), you are likely to be sent to the back of the line to get one: Not because you legally need one, but because they feel like it (i.e. they feel like having everyone give the same type of form), or because they don't know what they're doing. I would not recommend arguing with them and informing them that the older hand-written form is legally sufficient. It is usually better to do what they say.

So in conclusion, you can enter with the hand-written form. But you can also be asked (basically forced) to go to the back of the line and get the kiosk-generated form.

Probably the best thing to do would be to have your pre-filled hand-written form in your hand and show it to the staff standing next to the queues and kiosks. Say "I already have this, can I go to the front?" and you can get a positive or negative answer depending on who it is. If they let you go to the front and the immigration officer sends you to the back of the line, you're just back to roughly where you started, since you skipped to the front to get there anyway.

The electronic machines are a lot faster as there's no need for a human to read and check every form.

If you use a paper form, you're going to get at the very least increased scrutiny, and possibly will be sent back to the machines to use those.

That's just how a bureaucracy works.

p.s. on my visit to Montreal and Ottawa a few months ago there were plenty of machines, waiting times were almost non-existent, and using them only took 30 seconds or so. Explaining to a bored customs clerk why you insist on not using them and them then forwarding you for manual screening by some very interested colleagues who have all the time in the world to go through every nook and cranny of your luggage is going to take a lot longer than that.