Margen“I don't have time” almost always means, if you're honest, “this isn't important enough to me to take it away from something else”. And plenty of times that's perfectly fine: you can't do everything, and choosing is healthy.
The trouble starts when you say “I don't have time” about what does matter to you deep down — reading, calling someone, moving, thinking — and at the same time hand whole hours, unfiltered, to what you won't remember tomorrow.
Time isn't managed with more hours: there aren't any. It's managed with a single question, asked in time: “If this takes my evening, what am I not going to do?”. Every yes is also a no to something else. The question is whether you're choosing the no or someone is choosing it for you.