I think it depends on your makeupyears ago it helped me as I wanted to beat the guy better than me and there were a lot of them,now I just get so nervous I freeze and do the walk of shame back to the comp site
Getting lucky or making the effort to get some uncrowded waves is the key for improving your surfing.
Being able to take off on a wave in the spot you want to take off and knowing the wave is yours allows you to just think about riding the wave.
Get 20 or so good waves and its a huge step forward.
A heat to me just adds pressure although if the waves are good having time in the water in a heat with three others if you dont take it to serious can be another way to get some uncrowded waves
They can be a bit of fun or a learning curve, depending on the crew you surf with, how you take your surfing and the quality of surfing. I compete in a local clubs comp and it is all a bit of fun between surfing mates. Put you coloured rashie and go surf with mates for half an hour and enjoy a laugh and a beer afterwards.