Do you reveal all keys right after you buy a bundle? Should I?

Only on Humble. They are the only ones selling keys they don't have enough in stock of. And since Choice doesn't have choices anymore, it doesn't make a difference.

Fanatical has a 30-day guarantee for their keys to work and for the most part, they work a lot longer, but that all depends on the publishers.

Downsides to revealing without redeeming are no refunds and a very tiny risk (growing slowly with waiting time) of your key being redeemed by error/guess in the meantime without you being able to request a replacement because you can't prove it didn't work right after revealing it. And some publishers might even revoke sold/revealed but unredeemed keys after some time.

always, especially keys from HB

everything goes straight to the keylist spreadsheet.

I reveal every key after buying and use a spreadsheet. It's not that much work and in my opinion better than hoping, that the keys don't run out (looking at you, Humble Bundle).

I always get the game names and keys ASAP in my spreadsheet, along with the order page for reference (in Fanatical and Humble).

I also activate all games I want to activate the same day, but that's an habit of myself.

It is important to reveal the keys from Humble because you might not have keys available when you go for a game a month later. Or a day later. Or even an hour later.

I don't buy many bundles, but when I do I reveal basically right away, since I also tend to activate and give away as soon as I can, I don't have much keys lying around, but better safe then sorry!

I only reveal if there are key expiries. For charity bundles, i directly redeem all that im interested in because they might expire too. The rest i just left it as is. There are some that are several years old at this point.

Not always with Fanatical (it wouldn't hurt) but always with Humble, since they tend to run out of them for months to come.

So, I think you should do that as well with Humble, to ensure to have the keys you bought on hand.

I only tend to reveal and activate straight away those games I personally want from a bundle.
I always look at the leftovers as having no value (I don’t trade, too many frustrating experiences.)
I generally don’t sit on my spare keys for long though, they often get used in giveaways here within a couple of months.

I reveal everything right away and also give away any extras right after. I don't get the logic behind sitting on keys, especially for years like some people do. If I let them pile up then that's even more work sorting through them later.

I didn't use to, but now I do. The keys are safer in my spreadsheet than on a site that may go defunct (like desura, indiegamestore, groupees etc.) or run out of oversold keys (like humble).

activate all games i want myself - reveal other keys the moment i create a ga - so i know what keys are not used and good for ga

I don't. I really should, but I don't.