Imagine what it'd be like to only be able to speak to God during specific times throughout the day, or even the week. What if God only allowed our prayers to be heard on Tuesdays from 4–4:15pm? That any other time you'd call to Him, He wouldn't be listening.
If you needed help on an exam, or needed strength to get you through a tough time in your life—you had to wait until 4 o'clock on Tuesday to ask Him.
If you started breaking down in tears on your drive home because you felt the stresses of your life get to you, you couldn't cry to Him—because it's not Tuesday.
If in a moment of weakness, you committed a sin but regretted it right after—you'd have to hold on to your regret for another 5 days. You can't repent to Him. Because it's not Tuesday.
If you just got in a car accident and you were sitting in your wrecked car seriously injured—you couldn't call onto Him to help you. You're on your own. Because it's not Tuesday.
Fortunately, that's not the case. God is always there. He's always listening. He's always there to protect you, to guide you, to strengthen you. He has blessed us with the freedom to call onto Him wherever and whenever we need it. We take for granted the fact that He doesn't restrict time to our relationship with Him. Can you imagine how much more often we'd pray if we could only pray for those 15 minutes on Tuesday?
24 hours a day, 7 days a week, 365 days a year—He's listening. Are you talking?
And your Lord says, "Call upon Me; I will respond to you."
Indeed, those who disdain My worship will enter Hell [rendered] contemptible.
[Surat Ghafir 40:60]