Say for eg : You initiated with 2K following so here you get more chances where people out of 2000 followers will start following you. But when you complete 2000 followers twitter don't allow you to follow next 2000 followers it will only allow you to have 200 followers which means now the chance and probability of getting more followers has been decrease.
Apart from this there are many other ups and downs when you are trying to get more followers such as the limitations message from twitter - Although its one of the best discipline but i hate that as it just stop me to reach the hill.
You may also find people claiming to have 5000 followers in a day or 10000 followers in a week - One word for them - That's all fake. I don't say no but that's not real followers. Remember You can't have sales strategy with your twitter account - "what you show is what you sell"
Clarification - If i have 10000 Fake followers who will read my tweets, who will retweet my tweets so be careful on that.
there are lots of other's experience of mine which i will share on this blog
Remember - Be simple, Be powerful and always try to retweet tweet which you like - Give and Take policy