There is a lot of hating about the Kuva Liches but I personally like them and also how they are implemented. For me it all comes down on how fast I approach the farming and appreciating the process with all its side-benefits.
I normally get myself a new Lich every other week. I check what additional damage type would be nice and run a few normal missions for nightwave or riven challenges until a Lich spawns. The last one spawned on Lua while I was doing some Sentient with Loki.
After I get my lich I check the weapon, the stats and the lich's weaknesses. And then the murmur hunt begins. I honestly like that from this point on all my murmur missions are high level. I made it a habit to rotate through as many builds of as many different warframes as possible to check if they are still high level viable. The same goes for "forgotten" 3-6 forma weapons (ex-meta, ex-fun, specific playstyle, found-a-riven-for).
Apart from spy I do pub missions only and occasionally find a team mate or two. I do not care if people kill their liches because everybody has a different strategy when it comes to finding out the right mods in the right combination. I help them and they help me - that is the most important part of it. Tenno I meet during murmur farming are mostly chilled, well equipped and know what they are doing. It is pure joy to run along someone who knows what he/she is doing. It is the only place in the game where you can meet this kind of tenno regularly because other late game activities require either a strict meta (Eidolon, ESO) or a strict-ish weapon policy (arbitrations).
My murmur hunt lasts around 3-4 hours as I make my way to all nodes the Lich controls. Finding the murmur targets is easy and you can run all the old star chart missions you have probably forgotten about because of endless hours on the plains or the bleak Cetus mountains. I normally find around 5-6 relics during that hunt. That covers more than enough the one charge lost from the requiem mod. Then there is of course the new weapon or a lich stored away for the next big railjack update. The Lich fights are okay-ish when you have the right elemental / IPS combination for your lich weakness.
Cracking open the found relics is something for the following week. All new relics will be opened in Kuva Fortress. Higher level enemies are once again much appreciated and the rewards are nice. Riven slivers are a great way to get rivens outside of sortie and any duplicate requiem mod is a thank-you-very-much 50'000 credit cache. Spreading out the missions over the week makes them feel casual.
Defiled requiem mods I own sell for that-is-kind-of-you 25'000 credits and I have yet to have less than 2 requiem mods of the same type.
I am not the biggest fan of purposely burning myself out. That is why the inital hunt for requiem relics was stretched over two weeks with only Kuva Flood missions. That prepared nicely for rank 5 lich missions I had to face and gave DE time to fix the Lich system. In those two weeks I got 4-5 relics of each type, lots of Kuva and many credit caches (Orvius parts, Oberon parts).
This bi-weekly (over holidays weekly) cycle lead to 7 weapons and 2 duplicate weapons. From these two duplicates I sold off one lich to another player. As a vet I know what Warframe is all about and that rng sometimes work in my favor and sometimes it does not. I enjoy the way to a weapon more than it would ever enjoy a single weapon. I mean this is content for vets and vets already have 10-40 different super-awesome-room-killers to choose from.
Being able to bring each gun to rank 40 is a nice twist because it allows me to fit all primed mods I can think of on that weapon and still have place left for an exilus mod. Kuva weapons can totally do without a riven and still be awesome. That the process of going to rank 40 costs 5 forma is fine. Any great weapon in my inventory has 3-6 forma - not so different. Liches are for vets and vets will always have an amply supply of forma. You will build your daily forma, you get your nightwave 3-forma pack, you farm at least 20 forma in plague star and you will always have enough plat or 75% discounts to buy another 50-100 forma if you really had to.
If I could change one thing for Kuva Lich I would turn it into a weekly mission to better protect players from self-inflicted burnout.
Feel free to disagree.