Writings to Substantive procedure ……. pre year-end / post year-end

Hello ~ Tutor
When we do question about substantive procedure, the correct answer often related to
1.) pre year-end
or
2.) post year- end

I got confused ! ! In which circumstance, needed to use pre year-end !? In which circumstance, I need to use post year-end !?

I take a few examples of past paper to clarify my question as following :
Example 1
June 2013 Fox Industries Co (Fox),
Question(c) Describe substantive procedures the auditor should perform at the final audit to obtain sufficient and appropriate evidence in relation to the bank and cash balances of Fox Industries Co at the year?end

Answer writings :
1.Trace all of the outstanding lodgements to the pre year?end cash book, post
year?end bank statement and also to paying?in?book pre year?end.

2. Trace all un?presented cheques through to a pre year?end cash book and post
year?end statement. For any unusual amounts or significant delays obtain
explanations from management

Example 2
DECEMBER 2019 CBE SPADEFISH&Co ,
Question(a) Describe the procedures the auditor should perform to resolve the exceptions noted, for each customer during the positive receivables circularisation for Triggerfish Co.

Answer related to Flounder Co
1.If the difference is due to timing, such as cash in transit, this should be agreed
to post year?end cash receipts in the cash book.
2.If the difference relates to goods in transit, then this should be agreed to a pre
year?end GDN.

Answer related to Menhaden Co
1.If the difference is due to credit notes, this should be agreed to pre year?end
credit notes dispatched around the year?end date

when we proceed the answer, I just have no idea that when to use “pre year-end” !? In which circumstance, needed to use ” post year-end” !?

Thanks in advance