Programming in a whole fill would simply limit what you do to that fill rather than help you understand how to replace part of a measure with any fill you want. In simplified terms, using a metronome to practice fills helps because it keeps the basic quarter-note backbeat while you play grooves and fills around and over it.
Rather than map out a fill and copy it exactly, you should strive to put fills in perfect time with the backbeat of your programmed groove. Listen to where in the groove your loop is and play fills over it.
Think of it like a math test. Programming every little note you want play and playing it; you're essentially copying a "sheet" with all the correct answers to the metaphorical math test on it. Sure, you put in some effort in memorizing or copying, and you get an A... But you've also robbed yourself of really understanding the how and why those answers make sense and work. The greater your understanding of timing at a basic level, the better your timing, pocket and feel will be the more you work at it.
You should try and stick to a metronome or very simple programmed beat sequence to play along with if you want to improve your own sense of fills and time. I also like to play along to "hip hop" or other programmed commercial music when I get bored of clicks and want to work on timing. The key is simply a steady predictable beat. I can play around with it from there!