last sunday there was 5 bundles (collections) or about that
today there is 11
8 of that contains more than 100 games
it's takes ridiculous amount of time to check all of them
steam usually has 2-4 bundles simultaneously
may be it is worth to take the most successful game store as an example?

I haven't purchased a game here since 2016, so it doesn't really matter to me.

I haven't really taken note. I did noticed the unnounced surprise drop of Love 95, that's certainly 90% higher quality than most anything Kagura Games ever published.

I solve such dilemmas easily by never buying "bundles."

Bundles have become unimportant to me.
In the early days it was a good way to get started, often the games which did interest me cost more than the bundle they were part of.

But after all these yeary the bundles hardly ever contain anything that interests me, since I usually already own all older games that interest me and the new stuff doesn't get added to the bundles.

I think, the OP isn't talking about controversial "bundles", but about the amount of sales pages ("collections") currently active on the front page:
1. Cyberpunk essentials, 2. Classics, 3. Indie, 4. Best Deals, 5. RPG, 6. Explore by decade, 7. Games that last forever, 8. Speedrun THIS, 9. Whale Rock Games, 10. Major anniversaries, 11. NSFW

While I agree, that this is a lot of games to browse (if you want to), it is probably the only way for GOG to organize this massive summer sale of "5400+ deals".

what do you mean Steam have only 2-4 bundles? there are litterally 100's of bundles on steam, some of them are massive.

edit: for example - https://store.steampowered.com/bundle/13589/CASUAL_GAME_BIG_BUNDLE/. took me second to find

But ... you've got more choices, right? Isn't more choices better than less?

I don't think you're expected to look through every single item in every themed collection during a major sale. Prioritise the ones that interest you, and use the sorting functions for everything else.

There is really no reason to look at "bundles". I just go to the "Store" and then to "On Sale Now". There, either I check by genre, or I leave it unchecked, and then I check by some amount of price (usually by lowest).

Except if I absolutely know what I want. This sale period I bought Titan Quest and that will suffice.

A bundle with 100+ games? Ah, you mean collections.

I ignore all collections. I'd recommend doing what I do, and clicking on the big "Store" button on the ribbon at the top and enabling: Show only discounted, hide all owned products, hide DLCs and extras.

That way everything's in one pile and you can sort by price, discount, whatever.

If you want to look for DLCs, then replace Hide DLCs and extras for Show only DLCs for my games.