Multi-instrumentalists: How do you schedule your practice time?

This might also fall under General Instruction; however, since I am not specifically asking about bass I put it here.

I had another practice breakdown today where I realized that none of the practice I am doing is getting me to a specific goal, no matter how much I enjoy it. As much as I would like to be as good as Jaco, MM, Flea and all the greats, by trying to achieve that I am not touching my real goal in making music (specifically I would love to write and produce my own music). I know to do that I would need to improve my guitar and keyboard skills but I am afraid that, by removing focus from bass I will stop improving on that instrument.

So I am wondering, for those of you who play multiple instruments, how do you work the various instruments into your practice time to keep forward momentum? Or am I just going to have to bite the bullet and let bass linger in the background for awhile?