Flow is very important...My answer to your question is definitely yes
You should get enough powerheads so you have no "dead" spots in your tank
I have 3 in my 29G, 3 in my 54G, and 5 in my 225G
powerheads r a must. a tank with very little movement wont hv good oxygen exchange, which in turn will kill ur fish eventually. if u hv liverock, they also need good flow to do its job to act as filter.