I thump year round. In the spring not so much because the fish are shallow already and active. It will draw them around your boat more though so you can cast to them. Splashing works well then also. It mimics fish or bait on the top. Where thumping mimics fish eating bait at all depths. I’ve researched this a lot the last couple of years.
Thumper , we have had a great deal of success thumping while live baiting in July . Water depth plays critical role, however ! We don't thump in water 25 ' or less, anytime. Splashing works great in warmer months, use both .