the greeks dont matter to me on credit spreads. The only consideration for 5 contracts vs 1 contract is the commissions. A lot of traders take credit spreads by using the delta of the short and long puts, to me the critical components is having your support levels defined clearly so you sell you put as far below those levels as possible and still receive your 25+% credit. You can get down in the weeds on options greeks and make it much too complicated
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