Well for whatever reason, when I meditate, I usually do so lying down with my hands on the solar plexus area.
It seems to keep the energies more balanced as the kundalini opens up and flows in a sort of 8.
Re: the heart: There are actually two "heart" centers in the body. There is the unawakened heart, which is the thymus gland and resonates very strongly with what astrologers call Venus. It's primarily sort of a cyan color type frequency. It's nice and all, but it's very "personal love" oriented.
But then there is the "awakened heart", which actually relates to our actual physical heart. This part of us, resonates powerfully with the Sun and Golden Light.
This requires a balance and integration of the 6 other glands, as well as a mastering of the 6th center, aka the purple level.
Or in other words, the purple can lead to the golden light.
It's merging/balancing the awakened heart with the pineal, along with the other centers, that reveals the pure White Light of PUL.
It's never really about focus on any one center, dimension, color frequency or the like. It's always about balance, merging, integration.
Just as White Light (symbol for PUL) can become refracted into 6 main colors (think of these as 6 main dimensions or levels of consciousness) when it becomes unbalanced, so too in our energy system are we unbalanced/polarized, and need to bring it all back into harmony with one another.
You need a little red and Mars to get shite done in this world and to have a backbone. You need a little coral pink of the Moon of the "gut", you need some yellow Mercury of the intellect and left brain to understand and perceive things consciously, you need cyan of Venus to harmonize with others or deep green of Saturn's positive, teaching side for testing change to help bring balance, you need some deeper blue of Uranus to understand your creativity, will, self expression and the "fulcrum" point between the "lower" and "higher" parts of self, you need the violets and purples of Neptune and Jupiter to feel a more universal connectedness, to have the power of integration between the red and blue, etc, and you need the golden Heart of the Sun and Arcturus, well because you need Love to be positive in general.
Merge them all together one within each other, then you become the original expression, the White Light. You become like Yeshua and our Source.
Over focus on any one center, for lack of balance and integration, is not really particularly recommended unless you have a real strong imbalance in an area.
Say you're really, really, really yellow. Well, what's the opposite of yellow, but purple. Focus on purple can help to balance out the yellow. That's why the Mercury ruled Gemini and Virgo have their "opposite" signs as Jupiter and/or Neptune ruled Sagittarius and Pisces.
Hmmm, it's all an integrated system of "checks and balances".
Little too red and Martian, well, might be good to focus a lot on cyan and Venus to help balance that out. Hmm, Mars ruled Aries's opposite Sign is Venus ruled Libra.
These more extreme situations/imbalances are the exceptions to where you really want to focus on a particular center. Course, focus on the awakened heart is always a good, positive thing since it is such a fast vibratory and balanced vibration.
BUT, the Pituitary is even "beyond" read ,"faster vibratory" than the Heart. Just as White Light is beyond and faster vibratory than Golden Light.
Why not shoot for the Ultimate? Why be content with a limited expression/attunement, when self can have the fully Universal, fully free expression/attunement?
Put the receptive left hand on the Heart and the directive, Yang polarized right hand on the Pineal, and infuse the Purple with the Gold, and if you're doing everything else right and are otherwise close to the White Light, you might find your Pituitary becoming more active/awake, if Kundalini is flowing all the way to there and back, in a constant 8.