Quite. On one particularly hot (40deg C at sea level) day in Aus, with a PA28-161 at near MTOW and serious thermal activity I found the only way to climb meaningfully was to dolphin fly - the thermals were clocking around 10kts (1000fpm approx), up and down. Needless to say in the down bits the climb rate was negative!
Push the nose down and fly fast through the sink, haul it up and go as slowly as possible in the lift - maximising time in rising air, minimising time in sink. I did draw the line at standing it on a wingtip and circling in deference to the poor passengers who were already melting
We eventually got to 9500 where it was still something like +18, but a lot more comfortable - and smoother!