You also want to balance the time value and maturity date.
In the example I gave above, if TSLA rise very quickly to 400, you will not gain much, and could even lose a small percenage on those option positions, because March 14 calls would still have lots of time value left (ie, spread will not be big enough to make a profit). If you are worried about that, you want to play with shorter term maturity such as Feb 28 --- The trade off there is that you will not be able to spread 30 points but only 15-20 points.
Regardless, this strategy is a low risk play to catch a short term bounce, and you have to decide if you bet on very quick and short bounce, or a 2-3 weeks bounce :)
