Software Engineering is an interesting mix of practice and theory. On the theory side, you should make a habit of browsing / googling for things that are a good intersection of interesting to you and novel. Be forewarned, some of the common places to get information (like stackOverflow) can be very intimidating.
The standard expiration date for most checks is 180 days (six months) and personal checks are included in this policy. In the United States, banks are privately owned and not government operated so banks do have the right to refuse your deposit if there happens to be any suspicion of the item's negotiability.
Thanks for the A2A. Checks/cheques usually have a time limit or an expiry date. Most often it is 6 months from the date of issue (date on the cheque). Post this date you need to get a new cheque from the original issuer and later submit to the bank before its expiry date. Views.