My twins were nearing their first birthday last summer when a friend called. Did I want a part-time job as communications director at a not-for-profit organisation?

Although I love my career as a full-time freelance writer, the offer caught me at a weak moment. Day care bills were costing more than our mortgage, and the feast-or-famine economics of self-employment weren’t working so well anymore. Even with the superhuman support of my husband, the competing crises of my small business and even smaller sons made my life feel like a double episode of 24, except that instead of Jack Bauer, the hero was me, armed with a breast pump.

Maybe a part-time job, I thought, would solve my problems. After all, isn’t meaningful part-time work one of those “on ramps” that the economist (and mother of twins) Sylvia Ann Hewlett advocates to help curb the female brain drain?

I figured that if I worked 10 to 15 hours a week in the office, and another 10 to 15 hours on a few choice freelance assignments, I could earn as much as I did writing full time, smoothing out our cash flow. Meanwhile, I’d finesse the raging public debate over how mothers today should spend their time: I’d have more hours with the boys and I’d be working.

So last year, I became one of some six million moms — about a quarter of all working mothers — who work a reduced schedule. According to a new study from the Pew Research Center, an even bigger number — 60 per cent of employed women raising children — think that part-time work is the best choice. Can that many working moms be wrong?

In my own study, with a sample of one, I found that part-time work was not the answer. Although I liked the work and enjoyed my colleagues, I realised that Jack Bauer could never do his job part time, and it wasn’t a perfect strategy for me, either.

SURPRISE NO. 1 Crises require flexibility — and part-time jobs can be a lot less flexible than full-time jobs. Even if Jack Bauer spends an hour rescuing his wife or daughter or nephew from terrorists, he still has 23 other hours to find the bomb, recover the detonator and save the world. If he were working a reduced schedule, it would be the nephew or the detonator.

In my case, I worked on Mondays and Wednesdays. If I missed a day because of a sick child, an absent baby sitter, a doctor’s appointment or even a national holiday, I was suddenly missing half my week (not to mention half my pay). Sure, I could make it up on another day — if I could get childcare. But, at least in Sacramento, where I live, you can’t just send your children to day care on a Thursday instead of a Wednesday.

Part-time nannies don’t solve the problem, either; they’re usually booked on their days off. When I worked a full schedule, I also had backup care problems, but I could always make up the work somewhere. So in my case, at least, full-time work seemed better suited to the emergencies of a working mother’s life.

SURPRISE NO. 2 The sheet-protector problem. Jack Bauer always knows where everything is. He’s got a nifty drawer in the back of his SUV with an assortment of automatic weapons, hand grenades and tiny two-way radios, all neatly fitted into their own moulded compartments.

I, on the other hand, never learned where all the office supplies were, even after a year of part-time work. At least once a week, I methodically opened one cupboard after another, looking for a tape measure, a sheet protector or the right size of envelope. It was clear that I wasn’t building those small, unconscious office habits that make work easier.

And if I couldn’t remember where the sheet protectors were, what other important facts or habits were no longer at my fingertips? Friends who are part-timers tell me that their reduced schedules make them more productive. In my case, any gains were offset by the time I lost rummaging through physical or mental supply closets.

SURPRISE NO. 3 Every day was Monday. My part-time life felt like a perpetual series of jump-starts and halts, a kind of gas-stop-gas-stop cab ride. I’d work most of the day on Monday, forget all about the office on Tuesday, then spend Wednesday morning regrouping. A blank slate is great — unless it’s where you keep your to-do list.

Until every day became a Monday, I never realised how much of my ability to perform at a high level — to juggle multiple tasks, track deadlines, stay in flow and keep all clients happy — depended on my physical presence, day after day, working in the same place, on the same computer, on the same problems.

When I took the job, it seemed a fair deal to sell the organisation two days a week of my services. But before long, I felt as if I’d sold them the services of someone who wasn’t quite me, someone who needed to look at the manual to defuse the bomb and wasn’t always around to watch her colleagues’ backs.

It made me feel only worse to know that the organisation was making extraordinary efforts to keep me. It clearly irked my boss when I wasn’t around when she needed me, and she never could quite keep straight which days I was in the office. Still, she helped me delegate, gave me a raise and even considered hiring a second part-timer to share my job.

The tensions finally took their toll. I consistently put in extra hours; the office consistently scheduled meetings outside my allotted time. Then, one week, I realised that it was taking a full-time mental effort to make the part-time job work, and that I would rather put in longer hours at something I loved — my writing — than shorter hours at something I only liked.

So, I’m leaving the office and returning to a 40-hour-week of self-employment. Because, just like Jack Bauer, I’d really like to save my family and the world — and, at least for me, that’s a full-time gig.