To answer your question, the reason to deviate from this is preference. Some people hate a lot of chips on the table, others like it. To me, 'minimum' number of chips sounds cool and all and you definitely save money, but moar chips is not only visually more appealing and fun, but I also find that proportionality between the denominations helps in quickly assessing how much a player has in his stack.
My preference is (per player):
- 10 to 15 of the lowest denom chips
- 40 to 100 of the workhorse chips (4x or 5x the value of the lowest denom)
- A third and possibly a fourth denomination, of which the number in play should be in proportion to the amount of workhorse chips
- Add-ons / rebuys using only the highest denoms
Examples of chips per player for relatively deep and splashy games:
$.25/.50 cash game (NLH)
$.25 x12
$1 x47
$5 x10
$25 x2
That's $150 (300 BB). Think of it as 50 dollars in each of the three higher denominations, then make change with three $1 chips and you get you blinds chips.
Or for moar chips, use $1 x75 and $5 x15, with no $25 chips.
Another example using even moar chips
$1/3 cash game (NLH)
$1 x10
$5 x98
$25 x20
It's very intuitive seeing the rack of $5 and the one barrel of $25. And now you see why some people buy seven racks of workhorse chips.
That's $1000 (333.3 BB). If you think that's too much, you can always adjust and play 2/5 or 5/10
You could say that for tournament chip stacks it would be a different story, I disagree. Keep the lowest denoms with a reasonable minimum number of chips (they'll just be colored up) and use the same proportionality reasoning as above for the higher denoms. For example, for a 8-10 player STT T500 base tournament with a deep stack (300k), I'd use.
T500 x10
T1000 x10
T5000 x27
T25000 x6
Of course you could be much more efficient by using
T500 x10
T1000 x10
T5000 x7
T25000 x10
If hosting a tournament with a larger player base and more tables, consider the T5000 as a low denomination and keep the total number in play to a minimum before it gets colored up, introduce a T100k chip, possibly even 500k or 1M chips and use the same principle.