Finding and creating space in busy schedules to write, try stuff out, make meaningful progress through deep work or just to take a step back to think seems to be more difficult than ever. It's certainly something that I've long struggled with. And I think working from home, the endless Zoom calls and the increasingly blurred lines between work and life has simply served to exacerbate this.
Paul Graham's concept of 'makers and managers schedules' expresses neatly the challenge when calendars collide. If you're a 'maker' (a writer, programmer, or someone that creates things for a living) then you'll likely need good blocks of dedicated time to make progress with something. Managers however, will often segment their time into one-hour slots, and they are more likely to change what they're doing each hour. For the latter, a meeting can be simply a matter of finding a suitable one hour slot, but dropping a one hour meeting into the middle of a morning or afternoon can be disastrous for maker since it breaks up that half day into time chunks too small to do anything productive with. Managers can inadvertently end up making everyone 'resonate at their frequency', and making it hard for anyone to keep blocks of time clear of calls or meetings. As Mike Monteiro has described it rather than a useful tool for managing time, calendars can simply become a 'record of interruptions'.
It's easy to talk about saying no, and protecting the sanctity of cleared time in your diary, but a lot harder in reality to be that disciplined. I'm pretty terrible at it. So I liked Dickie Bush's concept of sacred hours. Sacred hours are those where you are genuinely able to focus on what you need to without distraction and where you don't have to suffer interruption. In order find the best slot to set this time aside you should ask yourself two questions: What time of day am I most productive?; What time of day can I be least responsive? This, as Dickie says, will be different for everyone but at least gives you the best chance of creating and keeping that time.