Sudden Improvement. ?????

You don't improve by winning games.

progress is typically 'nonlinear'

often u seem to be getting nowhere then all of a sudden u take a jump

Yes, it's called plateauing.  And most of improving from 700 to 1200 is just learning to drop pieces less often and take opponent's dropped pieces more often.

1700 to 2200 in 10 days would be a different animal.

you improve by practicing

not by winning games

Personally, I think you CAN improve by winning. Or losing. I don't see much difference between the two. Actively reviewing my own games, by whatever method (board, Fritz, etc.), has probably helped me the most. The trick is to be genuinely unbiased so you must be willing to study both your wins AND your losses. Not just the former. It's almost as though winning is overrated and losing is underrated.