Do startups usually equally split the company amongst founders?

IIRC Apple and Microsoft did. I doubt Facebook did.

Almost certain Facebook didn't, especially given the insane # of people claiming to be a Facebook co-founder.

Remember, vesting is almost as important(in my book, even more) than the % equity.

Of course, you want to get both right. Just don't forget the latter.

"It makes sense to equally split to equally motivate though."

Yes, otherwise you have one founder with all the weight on her/his shoulders and the others can end up like employees. It's not worth it: Result= Everyone's equity will be worth less in the end because they don't perform with the motivation of an equal team.

Also, being in that majority equity role really stinks. It's harder to take time off, people hesitate to make decisions without you...

I DONT expect work to be evenly divided tho. Just like in marriage, it is rare for a perfect 50/50 split of work. Some people are motivated to work until 4 AM each nite, and others are not. I think accepting that is important for a happy, successful partnership.

this depends on the dynamics of the startups , equally is good but not always appropriate. The equity split should always be proportional to a. quantum of pain or skin in the game [investment & time] & b. vested over 3-4 years

Equal is good when all founders are on it full time and have invested an equal amount of money but this is usually not the case