But the one thing that stays constant is the TV presenters.
These are the people who help us to cope with the early mornings - 6am starts, anyone? - and provide welcome distraction at 4pm when we're starting to flag.
So, after a few months - or years - of repeated exposure, it's not unusual to find yourself having very friendly thoughts about the very people who you once found annoyingly enthusiastic and, let's be honest, a bit cheesy.
You might think that it's your embarrassing little secret, but there are some clear favourites among mums.
"I get quite excited when Sid and Andy from CBeebies do their numbers dance," says Rachel, who has three-year-old twins. "I get the feeling that they'd be really good fun on a night out - and I secretly think that they're both quite sexy."
Then there's Mr Bloom - whose habit of talking to vegetables only adds to his appeal.
"When I was pregnant with my youngest, I had a filthy dream about Mr Bloom," admits Sarah, who's a mum-of-three.
"I'd like to blame it on the pregnancy hormones, but I still fancy him almost a year later. I actually think he's good looking, and I like his northern accent. Plus, the kids love him - and that's very attractive."
And, for those with older children, let's not forget Steve Backshall from CBBC's Deadly 60, who seems to have singlehandedly ignited a passion for exotic wildlife in British mums.
"I love Steve Backshall," says Amy, who has two sons aged eight and 10. "I'm not even embarrassed about it - he's got incredible arms. Every mum I know fancies him."
But is it wrong to have impure thoughts about the people who are paid to entertain our children?
"I remember only too well having all sorts of naughty fantasies about Phillip Schofield when my eldest son was just a toddler – I had almost forgotten about it until I became a regular on This Morning and there he was interviewing me without any knowledge of my secret crush," says behavioural psychologist Jo Hemmings.
"When we have kids our roles rather change from lover to mother and I think having a bit of a crush on a children's TV presenter is our, often subconscious, way of reassuring ourselves that we're still sexy and fanciable. And who can resist a handsome man who seems to relate to children so easily, when we're in that 'learning curve' phase?"
Tellingly, it only seems to be mums who have these crushes - or at least they are the only ones who will admit to it.
While men will happily chat about all the TV presenters they fancied when they were kids themselves - usually Michaela Strachan and Sarah Greene - it's rare to find a dad who will admit to fancying Kemi from Milkshake or Katy from CBeebies - no matter how well she can cook.
But then the typical dad doesn't usually give up work for months on end, watch his body change beyond all recognition, have to grapple with breast pumps or spend half their time covered in baby sick.
So forget Hollywood's latest hunk, when you're seriously sleep deprived, Nat from Iconicles can seem infinitely more appealing than fantasy man du jour, Christian Grey. At least Nat would amuse the kids for a couple of hours while you have a kip.
Who needs Fifty Shades of Grey when you've got fifty shades of Play Doh?
That's why children's TV presenters could be the ultimate thinking-mum's crush. I mean, what woman in her right mind wouldn't have her head turned by a man who is energetic, funny and brilliant at entertaining the kids?
But, I think we can all agree to draw the line at Sportacus, right?
The allure of Deadly 60
So who's your early morning TV crush or late afternoon secret squeeze?