In short, the answer is No. Your softener will perform best if it is programmed based on the true hardness and iron levels in your water supply.
When setting your hardness number, you are telling the softener how many hardness minerals are in your raw city/well water. To calculate this number, use our Hardness Worksheet.
Your unit uses the hardness setting to determine how often it needs to recharge. If you set the hardness higher than it needs to be, your unit will still give you the same degree of softness (0-3 gpg), but it will use more salt and water on the backside (more recharges). Setting the hardness number higher than necessary reduces the efficiency of your softener.