It depends on how long you can go without potentially receiving any payout. You can estimate the average time of finding a block at the current difficulty with calculators such as:
http://www.bitcoinx.com/profit/Of course, the average time to find a block that is shown by these calculators can vary greatly with your luck - you could be unlucky over any given period of time - so it a risk you take. If you are spending a lot on electricity to run your miners and you don't find a bitcoin block for 1 year then many people would find that situation to be financially unacceptable.
On the other hand, if you are mining with a pool, depending on your hashrate and the pools payout thresholds (and other things, like pool luck) you could be getting paid to your wallet each and every day.
In my opinion if you are mining BTC you should definitely use a pool.
(If you are mining altcoins then you may be able to solo mine and regularly find blocks, it depends on their current difficulty.)