No, you need to update it as soon as anything changes. Even, if is 15 days or 10 days, you still need to capture the entire flow of your employment. Yes, if in future USCIS asks for it, you will need to provide details. You should keep it up to date. Talk to your DSO, if you have missed updating anything and make sure you update everything. Also, keep all documentation. The reason for all of this is, in future, if they ask for any query during H1B application regarding your status, you should have proof of everything.