What Better Way To Have A Couple Or Individual Postal Stamp In The Collection?

I am an amateur, so I ask experts.
What better way to have a couple or individual postmark in the collection?

I have some postage stamp that are
- Two stamps in pairs
- Three stamps together
- Four stamps together
- Five stamps together

I plan, break out some groups, and leave only one stamp in the collection and the others I will change.
Is it good or not, for a collector of philatelists?

If the stamp's worth anything, my practice is to retain the multiple. As most stamps aren't worth anything, I don't usually bother retaining them, unless the postmark is attractive or it's a country that I'm particularly interested in, such as France.

All of the above.

Hi @GeoffHa
Thank you for your reply.
But,
How do I know if a couple of postal stamps are worth or not?
I can not be based on catalogue list prices.

I will wait for the opinion of the other members. I want to see different opinions.

As far as French postal stamps are concerned, I have about 267 pieces.
I am not interested in French postal stamps and I will exchange or sell them in the future. (Also another country: Russia, Poland, Hungary, Germany, DDR, UK and etc.)
I am interested in US postal stamps (which are not self-adhesive).
But that's a big process for me, and I'll do it slowly. (I am an amateur and I do not have enough knowledge).

Hi @Stallzer
Thank you for your reply.
I see you have the same opinion as @GeoffHa.

So all the indications move in the following direction:
I need to sell or exchange of individual stamps and leave grouped postage stamps (if possible).

On my homepage you can see part of my collection (I currently uploading all my stamps on my blog). I'm interested in your opinion about stamps that have a printed serial number on the margin. If you have free time. If not, all is OK.
Best regards to both.

Post a picture of the margins you are talking about.

Hi @edgarsrasa, thanks for reply.
I am a new member and I do not have 50 posts. I did not know I could put pictures on the forum.
Here are some examples:

I posted few images, But my post has disappeared?
------ EDIT ----------------
My Apologize, post is here.

Leave the multiples with plate numbers intact. With regard to the cancelled multiples, I see no reason why the pairs could not be broken into singles. My personal preference would be to leave the used blocks of four or six as is.

@dudley
Thank you for your advice.
I have it yet, but I'll upload it all to my blog.