When it comes to deadlifts, most people select either sumo or conventional (whichever you feel better at) and stick with that lift. Depending on your anatomy, one will typically feel better than the other. While mastering just one of the techniques over the other has its advantages, leaving the other technique undeveloped is to leave adaptation on the table. My suggestion is to incorporate both techniques into your program – especially if you are in your first year or two of training deadlifts.
This can be done by alternating which one you emphasize each week. For example, if this week you plan to pull conventional as your working sets, finish the training session with sumo while focusing more on technique rather than weight. This is also an opportunity to incorporate assistance/accommodation. By that I mean when you’re pulling sumo, use bands, chains, slo-mo deadlifts, pause deadlifts, deficit pulls, snatch-grip pulls, rack/block pulls, etc.
Now that your last week was conventional deadlift-focused, the next week should be a role reversal. Start your training session with working sets of sumo, then switch to conventional while focusing on technique, assistance, and accommodation.
BONUS TIP: Keep your deficit pulls no higher than 1 inch. Going higher (deeper) than that, the mechanics of the lift changes dramatically which limits the carry-over to the movement you’re actually trying to train. But more importantly, the risk:reward ratio becomes much more skewed toward the risk side of the equation. To do deficit pulls safely, it really challenges your mobility/stability to maintain safe positioning throughout the movement. Above an inch or two, it’s just not worth the added risk of injury.
SUPER BONUS TIP: Unless you’re an advanced competitor, give up rack/block pulls that set the bar above your knees. Oftentimes, an athlete can pull an awful-lot more weight by pulling from such a high position and disguise the ego-enhancing lift by writing it off as supra-maximal/ partial rep training. There just isn’t a lot of carryover to the deadlift movement by pulling from a position this high. It’s just not a good investment of your time at the gym. When you do a lot of partial reps, you get good at just that; partial reps. Don’t get me wrong, partial reps and supramaximal training certainly have their place. But let’s keep it within a useful range. If you’re going to do rack pulls, limit the height at your knees. Also, you can still get the benefits of supramaximal training but keep the range of motion carryover by utilizing reversal bands (instead of anchoring the bands to the floor, anchor them to the top of the power rack.)