When setting your calendar, you allot time for known to-do's. How do you account for unknown things, such as incoming calls and un-planned urgent issues?
It is hard to give you specific advise without knowing better your situation, however, I would say unless you are a doctor and lives are in your hands, incoming phone calls can wait. They should not be a reason to break your focus and stop an important task you are working on. Making this shift often requires training of those who are used to used to you always pick up the phone but it can easily be done and it might prove to actually lessen your calls as often people will figure things out for themselves if they know you are not at their beck and call.
The second is that you can not schedule urgent issues and shouldn't try. You can however assist others in understanding what is an urgent issues. We too often take others' sense of urgency as our own when they really are not urgent.
You can not foresee every task that will come up, that is the fluid nature of business, however this is why it is important to set your priority tasks each day and ensure that you do have uninterrupted time to work on it.
Also instead of blocking out all your time each day for specific tasks, instead block out time for types of tasks. IE: priority task, phone calls, email. Emergencies might eat into your time on a set of tasks, but hopefully you will still have time to work on the most urgent of the set or take over a non urgent set to complete the tasks that got interrupted, when rearrange a day later in the week to catch up.
Biggest thing I tell all of my clients is that you need to treat the time you block off for your priority tasks just as you would an appointment with a client. Nothing, barring a severed limb or office fire should keep you from focusing on that task. Everything else can wait. :)
In order to know how long it will take to complete a task, you must have done pretty much the same already. So, you need to repeat yourself to be able to plan. The core mantra in software engineering, however, is: Don't repeat yourself. If you do anyway, you are most likely reinventing the wheel. In that sense, if the duration of a task is predictable, the task is most likely worthless. It will have little or no value to carry it out. It is the nature of the beast that it is utterly unrealistic to allot time for known to-do's in software engineering. Also, there is no other profession outside technology in which people would think that "disruptive" is a synonym for "excellent". In technology, however, "disruptive" has the sonority of billions of dollars dropping out of the sky.
I did a study. 1. Calls- Most were a one way delivery of information, or outside the four corners of an agreement.
If a one way delivery of information, set up a process to eliminate the call next time.
If a contract violation, repeat the policy, cite the agreement, get a contract admin or lawyer to fix the problem.
"urgent issues" are usually a contract violation, lease violation, or broken promise of some sort- assign them out to be a part of an improved business process.
I invest a TON of time in each and every "event" because I used to be in a wholesale business - sold billions of phone calls, and had to set up trouble tickets for "bad calls" which had to be cost effective, and worked with an unlimited supply of in house legal support. Once you can't "snap your fingers" to "fix something" with unlimited in house support legal and contract support- you strike out on on your own, yet, oddly the logic is still the same. You can still use the experience to whittle away at the annoyances. I gained hours and hours after I did this for a year- change 1% a week and half the process is reconfigured after a year, right?
The rule of thumb is that you will never be more than 80% efficient, and most workers are not more than 60% efficient. So if you book your schedule with more than 2/3 of your time committed to specific appointments and tasks, you are likely already full.
Being able to effectively prioritize activities is a time management skill you will benefit from developing. The biggest time waster is starting and stopping tasks (interruptions). It takes time to get in gear for a focused task, and time to wrap it up. Your thought processes are different, you need different resources, etc. MOST people are terrible at juggling, which is why you see the efficiency rate so low.
Stacking and grouping tasks that are singularly focused in as big of chunks as possible is much more effective than flipping between unrelated things. Our brains are too easily distracted and chase stuff down all kinds of rabbit holes that we wouldn't do if we stuck to our plan. Most outsiders are willing to be patient with you if they have their expectations set properly.
For example, set three times a day to completely go through all of your email. Once when you first start the day to become aware of any urgent issues, once after lunch to catch up on any new issues that may need prioritization, and once at the end of the day to respond to anything that did not need an earlier response one of the two previous times.
There is a productivity study that says working in chunks of 52 minutes and 17 minute breaks is the most productive. That means an intensely focused task for about an hour, and then an interruption for 1/3 of that time. This is about 75% efficiency, the most you can expect for most people. https://goo.gl/n14J3i
If you're not the only one in your office, delegate a filter. If you're the boss, someone else's job should be to know what needs escalation to you and what doesn't. Let other people help you with this and receive fewer interruptions. Work on your 1 hour on 20 minutes off schedule, and folks will know when it's okay to pop in with an interruption. Use the door on your office (if you have one), and close it when you're focused, and reopen when you're okay with interruptions.
It's discipline, but throw out the idea that you will ever be able to book 100% of your time.