Old school drum programming - 909 etc

I've recently made the decision to switch the computer off (too easy to get lost for hours with no tangible output) and get busy programming my tr909. But I'm having a few problems trying to find the best way to go about it…

I've been composing the whole loop on one pattern, copying that out across 16 patterns then going into each one and deleting bits out. But this seems kinda inflexible, as in if you want to change something half-way through then you need to recopy it out.

The other way of doing it where you'd just copy the patterns out as you write them seems a lot slower to me and you need to be stopping the sequencer all the time.

What I really want to find out is how to organise the patterns so you have the scope to do lots of variations & fills - the kind of programming you used to hear on Slam tracks back in the day.

Any help would be hugely appreciated…thanx