From a data analysis point of view it would be better all on one sheet, with a column for week number, then put a filter on the week number so only current week is showing. Large amounts of data are always easier to analyse as a single block than spread between sheets.

You can then create pivot tables from the data (e.g. to analyse week-to-week or month-to-month trends), easily use functions such as SUM, SUMIF, SUMIFS, COUNT, COUNTIF, COUNTIFS and so on. From an analysis point of view, lots of separate sheets are frustrating....

If you're creating data blocks to be analysed, I'd also advise STRONGLY against merging cells. You need to be able to select individual columns, and that gets messed up by merged cells. It's usually unnecessary anyway...