@barrenriverjohn said in #1, #3, and #7:
> ... I am a low-rated player studying the Ruy Lopez with white, and I am trying to learn when to play d4. Does anybody have principles or "rules of thumb" you might share? ... [Karpov] plays [d4] early, and other times waits -- so it's already clear to me that this is not a simple or static question. ... I am mostly interested in how other folks learn to "feel" this decision, ... Take, for example, white's response to 3...d6 (the Steinitz Defense) ... as [Ben10Tenyson points] out, both [d4 and c3] are viable. I guess I am trying to learn for myself which paths suits me better, ... Ideally, I would love to hear more experienced players say things like, "I like to play d4 early, because it allows me X, Y, and Z" or "I generally like to develop the position first, because I have noticed X, Y, and Z." ... Knowing Lasker revised his thinking after so many years makes me feel like I am asking a good question!
I fear that you are not likely to find the sort of answer that you are hoping for. The book, Understanding the Spanish, notes that, after 1 e4 e5 2 Nf3 Nc6 3 Bb5 g6, 4 d4 "is White's sharpest approach", and, after an illustrative game, continues with:
"We now turn to a slower pattern of development for White which gives the game a more positional flavour. White concentrates on erecting a formidable centre with c3 and d4, which in turn produces a space advantage after d5. ..."
A game with 3...g6 4 O-O Bg7 5 c3 a6 6 Ba4 d6 7 d4 is presented.
The same book offers 4 d4 as a reaction to 3...d6. ("White strikes immediately in the centre.") Two games with 3...d6 4 d4 are presented.
It is a pretty daunting project to undertake to study the Ruy Lopez. Right off, one faces the prospect of potentially encountering 3...a6, 3...Nf6, 3...f5, 3...Bc5, 3...d6, 3...Nge7, 3...g6, and 3...Nd4. I don't think that there are "X, Y, and Z" principles that apply to all of that sort of thing. It is perhaps not surprising to see the advice in Journey to the Chess Kingdom by Yuri Averbakh and Mikhail Beilin:
"Alekhine advised beginners not to play the Spanish game. We also recommend you get some experience first by playing relatively simple openings - the Scotch and Italian games - and only then move on to the Spanish one."
It is possible to play a somewhat simplified Ruy Lopez.
"... As a first step in mastering the Ruy Lopez, you need a solid, simple repertoire that will allow you to play practice games with your new opening without fearing nasty surprises. ... 1 e4 e5 2 Nf3 Nc6 3 Bb5 a6 4 Ba4 Nf6 5 d3 ... This should be by far the most common position you reach after 3 Bb5. Until, that is, you feel ready to branch out from 5 d3 to other, sharper variations. ..." - The Ruy Lopez: Move by Move by GM Neil McDonald (2011)
In First Steps: 1 e4 e5, GM Emms wrote, "... you certainly don’t need to remember every single variation and all the notes before playing the opening. Take in the first few moves and the key ideas, and then try it out in your games! ..."
GM Nick de Firmian told his readers that, after 1 e4 e5 2 Nf3 Nc6 3 Bb5 d6, "4 d4 is the best and most forceful move", but he also wrote that the "moves 4 c3, 4 O-O, and 4 Bxc6+ bxc6 5 d4 are all sensible and give White chances for advantage".
"... I am not a big fan of weaker players memorizing lots of opening lines they will never play. However, it is quite a different issue to spend a small amount of time learning how to play your openings a little better each time they occur. A long journey begins with a single step. ..." - NM Dan Heisman (2005)
web.archive.org/web/20140627023809/http://www.chesscafe.com/text/heisman50.pdf