chasing my b5 bishop in the Ruy Lopez

after I play Bb5 black often plays a6 and so I play ba4 to keep attacking that diagonal. Sometimes b5 is played and my bishop must move to b3. Is this good or bad for me? My instincts tell me that i just moved the same piece 3 times and black developed a decent pawn wall on the queenside. Given the popularity of the Ruy Lopez i feel that this seemingly obvious continuation must be bad for black, but I dont know what to play against it.

It's very common in most Ruy Lopez lines.  It's not at all bad for White, but if you don't like it you could play the Exchange variation (1. e4 e5 2. Nf3 Nc6 3. Bb5 a6 4. Bxc6)

It's on a great square on b3. The black pawn moves can be an advantage (space advantage, allow development of the bishop), but also can be a target i.e. white can play a4 to attack then.

Black:  Ha!   I made you move your bishop!

White:  Ha!  That's where I wanted it anyway, dumbdumb!

and could you or anyone else elaborate why thats the diagonal i want it on?

One thing a bishop on b3 does is point at f7 (not that I'm sure whether that's typically relevant in the Ruy Lopez).

Of course, the bishop often ends up on c2 shortly afterwards when black plays Na5 (the Chigorin, to name one variation).

Now would someone explain why ppl would play it when you have to move same piece 4 times in the opening? Isn't it against the simple rule not to move any piece more than once in the opening?

Moving the same piece multiple times is bad if the opponent can use the time for a productive purpose. If he just uses the time to weaken his Queen-side Pawns and drive your Bishop onto a secure, aggressive spot (Bishop on b3 is guarded and pressures d5 and f7)... just how is that bad for you or good for him?

And you feel that a5 is a wonderful centralized post for the Black Knight?

My point is that messing around with one piece is only a problem if the opponent is making good use of the time gained. If he is also wasting time, or weakening his Pawns, or decentralizing his pieces, then where is the harm?

get you

thanks

No problem.

I was just wondering about this set of moves. I'm very lacking in knowledge of names and openings, but I'm not surprised that this is a defined sequence. Good to know consensus is that it's mostly worth it for white. What are some ways to capitalize on that positioning?

If you mean... "How can White capitalize on Black weakening his Q-side and chasing the Bishop to a better square by a6/b5?", then here's one possible sequence of moves: