Stamp Collecting Query

How many duplicate stamps should be kept? With my stamps I have only one copy of some, others 3 or 4 extra and others I have 25 to 30 extra. What is the best way to determine a reasonable number of copies and should all the duplicates be stored separately in stock-sheets or glassine envelopes? Would appreciate any suggestions from the community. Thank you.
Honeydo.

Keep all, and experience will eventually dictate.

Keep in mind, you may wish to isolate, now, or in the future.....
Perforation differences,
Watermark alignments
Known flaw issues
Postmarks
Paper difference
Helecon..

etc & etc.

I keep mine in paper envelopes, when I have a page or two, place on ebay,
or donate to your favourite stamp club, charity, give away here...

It really depends on how you want to collect. Keeping one - or a mint and used version of the same stamp - is entirely normal. As Rod says, if you want to delve deeper, or think that you may in the future, keeping more may be useful. But there's no "need" to do so. Most will keep duplicates in stock-books, glassines or envelopes. Do beware of assembling piles of duplicates that fill up your house, though!

I am in the keeping only one camp except for a select few when there is a color variety. You can try to trade the duplicates to obtain more of what you need.

Thank you for the responses to my query. I shall keep what extras I have so far to check for any differences as suggested. When or if I become overloaded with duplicates, I will venture into trading for a missing stamp in a series or donate to the stamp community. I am in awe of this forum and its members that are willing to give and to share advice.
Honeydo