If the company continues to get same substantial value from your work, yet they're bugging you about the number of minutes it took you to do it, then they have their priorities backwards.
There are cases when timing matters, such as if you're expected to collaborate with internal teams who have set schedules, but that has less to do with how many hours you spent doing X.
I think it's more a question of morale: if you're the freelancer who waltzes in and out when they please, how's that going to play with the guys who have set hours?
I've had this thrown at me on multiple occasions, at gigs where I've solved and addressed long-standing problems, hugely improved efficiencies, and taken systems from states of perpetual chaos to vastly smoother functioning conditions.
And the simple truth is, I will lose my effectiveness and sanity if I'm required to put in "face time" simply to maintain order elsewhere.
Ultimately I view complaints on that basis as an exceptionally strong indicator of management incompetence. Time to look elsewhere.
Although I understand what you mean, I don't think it's your job to worry about others' morale. Yes, they have to stay there while you get to come and go, but they have job stability and you don't. You are taking a bigger risk than them, and having flexible work hours is your reward.
That's a nice way to view it but as a contractor/freelancer part of your job is getting and retaining contracts. While a big part of that is the work you do and the results you produce, people pleasing and team fit play a part as well. It's a legitimate concern since FTEs often complain about different rules and regs for contractors while forgetting about their own holidays and other benefits. Yes, your supervisor/company contact should handle it and, technically, dictating your hours can be playing fast and loose with IRS 1099 laws but, depending on your relationship, it can be better to conform in some areas to have more leverage in others.
If you bill daily, and waltz in around 10am when the company has been open since 7, and then waltz out at 2 when they stay till 4... it may be a little challenging to convince anyone that you really accomplished a full day's work ("well, if you had been here that extra few hours, we could have gotten X finished today", etc...)
Nobody said when you charge daily/weekly you get to slack off. You absolutely have to deliver the value if you want to keep getting contracts and referrals. Billing daily or weekly helps to refocus the discussion from a metric that people very commonly attempt to micromanage and pick apart (hours) to a metric that actually benefits the client: the ROI of your services. Who cares if you worked 15 minutes extra on Tuesday and left 10 minutes early on Thursday when you can show to your client that your ROI is 300%?
When I leave at 3 in the afternoon because I'd like to pick up my kids from school for once, I'm not "slacking off", but I'm definitely taking time that could have been employed productively, so I don't think I would feel good about charging for a full day. When I stay until 8 to fix something, I kind of want to be reimbursed for the extra time I'm putting in.
You spent time on their stuff that day instead of working on something else or some other client. The opportunity cost to you is the same, whether you leave at 3pm or work until midnight. Charging by the day or week allows both you and the client to not think about low level implementation details like that.
The inverse may be true however. If you skip out 1 hour early every day but still accomplish a lot in your opinion, the company may feel that if you had stayed that one extra hour each day, over a week's time you billed them for a full day that they never received.
They may argue you could have accomplished the task 1 day early, saving them $X, etc.
I agree with your value proposition -- but I feel it's difficult to pull off in reality. I feel a lot more comfortable with billing Time and Materials rates, so basically if I skip out early one day, they aren't being billed for it, and the project goes on at it's pace.
If you end up working out of their offices and on their schedules, you're already blurring the line about being a contractor in the first place. More like a temp really.
Hmmm.. I can see that, just like you wouldn't reveal your salary for morale reasons.
Maybe close a couple of issues/send a bunch of emails at night so that people see you are not done at 5PM sharp? Visibility does not have to be physical, like "body in the office", but digital also.
There are cases when timing matters, such as if you're expected to collaborate with internal teams who have set schedules, but that has less to do with how many hours you spent doing X.