Component percentages (Excluding cables)

My 2.1ch system today would cost, street price, around $20,000 (if New). It cost only a fraction of that in reality, just putting it into context.

As I've arbitraged my way up the audio food chain, my focus on certain components has changed, as their overall impact on my system changes at different price-performance levels. At current street prices my system would breakdown like this :

Integrated: 25%
Streaming DAC: 20%
Speakers: 20%
Sub: 5%
Secondary sources, cables, shelves, isolation, etc.: 30%

Purely from a % view, my speakers and sub need upgrading (the sub was for my HT system but I moved it into the 2ch room temporarily). 

I like the idea of investing 50% into speakers and 50% into everything else, but I'd include a sub with that (only one, can't go dual).

Do any of you try to balance your system using a % allocation like this? If so, have you found a formula that works well for you? I find it really helpful, because I'm not assigning a dollar value to anything, just setting guidelines for overall investment balance.

Thanks in advance!