Is it necessary to clean every record?

Only if you're obsessive compulsive. I clean records that appear or sound dirty. It doesn't always help, but at least I give it a try. With brand new records, I don't usually clean them before listening(I know, burn me at the stake). If I don't like them, I'm not going to keep them and it seems a waste to spend time cleaning them until I'm sure. By the way, I use a Nitty Gritty 1.5FI and it takes me a minute and a half max to clean both sides of an LP.

Not only every record but everytime it's played. At least in my experience this gives the best long term results. any dirt, even surface dirt, can be ground in by the needle. If the record is cleaned befor play this reduces the possibility of this. To me, it's less of a sonic benefit than a long term, record lasting benefit (as records are expensive and sometimes difficult to replace). Some people use a carbon fiber brush for the "in between" deep cleanings. This dry method gets rid of most of the loose dirt, but I still prefer using the machine to clean each time--I guess it is obsessive compulsive at that point.

What I do with used records is to clean them with my Nitty Gritty, then treat them with Gruv Glide and place them in a new poly lined sleeve. I wipe the jacket with a slightly dampened cloth and, after drying, store in a "japanese" resealable cover. I put a "GG" on the cover with a magic marker. This way I know an album is clean and the need to reclean is minimized by using a new sleeve and cover. The cover also protects the jacket from deterioration. I usually do the same with new vinyl.

Yes you have to clean your records.It is a must its like driving a clean car vs. a dirty car the clean one always rides better and the music sounds better.

That is part and parcel of the great world of vinyl. Why forego such a treat. Even the dirt that you don't see can affect the record. Firstly, it may not sound right, secondly, you can damage the record permanently by having the stylus go trough miles of crud. You have the machine so why not use it. Call it work. Call it a ritual. Just do it. Have cds spoiled you or what?