The cialis tablets are teardrop shape, and not scored, so cutting them into quarters is problematic. I lose a lot to dust - put all that in a pill bottle, and when it looks like a lot, I'll add that with a short quarter. I'm pretty sure my daily dose is never 5 mg. My Rx is for 20mg tablets, because the insurance covers only 8 per month regardless of strength.
Can't say what taking a 20mg every day would do - with the back pain I see at 5mg, I won't even think about trying it.
Have not tried others yet.