If I call in sick to work, or if I'm on vacation, no, it's not OK to call me for "just one quick question". No, I will not VPN in to approve a contract. No, I will not call in for a meeting. No, I will not read your email and respond. I have the day off. I'm using time that I've earned and accrued. If I'm sick, I'm probably sleeping. If I'm on vacation, I'm taking a break from work. What you're asking is the opposite of both those things.